Accessing SSD of dead MacBook

If 

diskutil list 

comes up empty, software recovery isn't going to help yet. The Mac literally doesn't see the storage device, just the USB bridge (which is why you see it in System Info).

Since it's an older Mercury drive, I'd bet money the enclosure power or bridge chip died, not the actual SSD inside. Crack that case open (if it's the SATA version) and plug the drive directly into a cheap SATA-to-USB adapter. I've saved a few "dead" drives that way where the drive was fine but the box failed.

Since the drive shows in System Information, the SSD itself is probably fine, you’re dealing with a damaged APFS container or partition map, not a dead disk.

The safe way to get your files back without making it worse. First, on a working Mac, open Terminal and run diskutil list to confirm the external is detected (you’ll see something like disk2). If it appears, do not erase or run First Aid repeatedly. Your priority is to clone the raw disk to another empty drive using dd or a disk cloning tool so you’re working on a copy, not the original. Once cloned, try mounting the clone with diskutil mountDisk diskX. If it won’t mount, use a Mac Data Recovery Software that can scan APFS containers directly, these read sectors without relying on the damaged partition map.

Recover the files to a completely different drive, never back to the same one. For the internal 256 SSD, remove it, place it in a compatible enclosure, and follow the exact same logic, detect → clone → recover. Idea is simple, stop writing, clone first, recover from the clone. That gives you the highest chance of getting everything back intact.

That means either the SSD inside has failed or the SATA-to-USB bridge is partially malfunctioning under load. At this point I wouldn’t waste time on filesystem theories, if diskutil can’t see a disk node at all, APFS corruption isn’t the issue.

Pull the SSD out of the Mercury case and connect it using a different, known-good SATA enclosure or dock. If it suddenly appears in diskutil list, the original enclosure was the culprit. If it still doesn’t show up anywhere, even on another Mac, then the SSD itself likely failed, especially if it was being used as a boot drive and got hit with heavy writes before the crash.

Just a heads up before you try swapping them — the 2015 MacBook Pro internal SSD is not standard SATA. It uses a proprietary Apple connector (12+16 pins).

Unless your Mercury enclosure is specifically an OWC Envoy made for Mac blades, the internal SSD physically won't fit or connect to it. You need a specific enclosure designed for "Apple Flash Storage" (2013-2015) to read that internal stick via USB. Don't try to force it or you might bend the pins.

Right now I’d focus less on Windows compatibility and more on why the external suddenly stopped mounting, because that’s usually enclosure, cable, or power related rather than filesystem corruption.

Those Mercury On-The-Go Pro cases use a SATA bridge board, and when they fail, macOS won’t even see the disk in Disk Utility or System Information under USB, which makes it look like the SSD died when it often hasn’t. First check on another Mac and look in System Information > USB to see if the bridge shows up at all, if nothing appears, it’s almost certainly the enclosure, not the drive. In that case, yes, pull the SSD out and put it in a known-good SATA-to-USB enclosure and try again.

As for Windows, it won’t natively read APFS or HFS+, so don’t reformat anything until you’ve recovered what you need. And definitely don’t put Time Machine on ExFAT, it breaks how macOS handles snapshots and metadata. What this really means is, recover first on a Mac, verify the SSD health, then decide on a cross-platform strategy for separate storage, not your Mac backup disk.

kaz-k wrote:

I think Windows laptop can't read APFS drive.

Windows would not be able to read either HFS+ or APFS filesystems without the help of a third-party package such as MacDrive .

ninjaphrodite wrote:

I just got the Mercury last year & wasn't able to start using it til Jan, so it only lasted a few wks. Don’t think it’s SATA.

https://www.owc.com/solutions/mercury-on-the-go

The enclosure you linked here is for a 2.5" SATA SSD which Apple only used in the Unibody laptops (and older).

Is this a Retina model laptop or just a Unibody model?

You can get the exact model by using the Apple check coverage page here:

https://checkcoverage.apple.com/

The Retina model laptops have a proprietary blade style SSD & connector which requires a special OWC Envoy Pro Enclosure assuming the internal SSD is the factory Apple SSD and not a third party replacement.

Assuming a Retina model laptop with an Apple OEM blade style SSD:

https://eshop.macsales.com/search/?q=envoy%20pro%20enclosure&filter.catidpath=4353&filter.dimension_type_135=Bare%20Enclosure%20Only

If it has a third party M.2 NVMe SSD with a third party SSD adapter, then you would need an appropriate M.2 SSD enclosure. So you must know the exact model of SSD.

Good to know they might not be swappable, before I take them out! If there’s anything I need, I want to get it beforehand, so I don’t leave them exposed longer than necessary.

FYI, all things being equal....the SSD is the weakest link if the SSD is not physically seen by the system. An SSD completely disappearing from the system & not communicating is the most common type of SSD failure. If the Logic Board has suffered liquid damage, then perhaps the SSD supporting circuitry has been affected by the damage. I never encountered a normal Logic Board failure which affected the blade style SSDs of the non-USB-C Macs.

Using the Terminal app, you can use the following command to see whether the physical SSD is seen by the system:

diskutil  list internal  physical

Now, things get really complicated if you happen to have a third party NVMe based M.2 internal SSD installed. Since you now have an SSD adapter that could be causing problems (there is only one brand of internal SSD adapter that appears to work reliably). In addition, if you are using an internal third party NVMe SSD....you must be booting from macOS 10.13+ in order to even see the physical SSD while it is installed internally. Older versions of macOS cannot communicate with a third party NVMe SSD so the physical SSD won't be seen. Make sure when booting into Internet Recovery Mode or from a USB installer that you are booted to macOS 10.13+.

You really need to take your laptop to a local Apple specialist who understands these complexities. Unfortunately an Apple Store tech won't have this knowledge. It is hard to say whether an Apple Authorized Service Provider will know these things...it all depends on whether they have previously supported these custom hardware configurations. This is specialized knowledge. Someone without such actual experience & knowledge can declare an SSD dead when in fact they the operating conditions are not being met.

One quick & easy way to check the internal SSD without spending any money is by creating & using a bootable Knoppix Linux USB stick. If you have any friends, family, or co-workers who are familiar with Linux, then this could be a quick easy way to get some quick answers. Unfortunately if you are not familiar with Linux and the command line, then walking you through all the steps is too much for a forum post. The Linux system logs can quickly tell us if the internal SSD is communicating properly or throwing up errors. It can also identify the SSD if it is communicating & run a quick health check on it. It won't, however, be able to access the data on it since accessing APFS volumes is poorly supported on Linux (and complicated). Let me know if this could be an option & I could provide basic instructions if someone is already familiar with Linux. Unfortunately macOS is not very good for troubleshooting these issues.

Edit: Knowing the exact model of this laptop is important. So many people mistakenly call a unibody MBPro (mid-2012) model a 2015, 2016, etc. because they purchased it in those years. The unibody 2012 model was sold for a lot of years (one of the longest runs I can recall).

Hi,

You can pull out external SSD from 2015 MacBook Pro and it put in external enclosure to salvage data on it, though you need another Mac. I think Windows laptop can't read APFS drive.

Is this the same SSD & issue you had in your other thread here?

USB wont mount, how can I recover data? - Apple Community

If so, you should have continued posting in that thread since it includes lots of relevant troubleshooting information. I'm sorry I did not respond back there, but I had a lot of personal & work things going on in late Jan. Due to the complexity of that thread, I needed to have sufficient time to think & analyze the information provided to provide the next best step in troubleshooting. Unfortunately I did lose track of that thread so another post there would have reminded me to post back.

If you confirm this thread is about the same issue, then I will review the information from the previous thread to suggest the next step. There is a lot of information to parse through to determine what details are important & which should be ignored. And please confirm the size of this SSD.

ninjaphrodite wrote:

I’ll get a compatible MacBook for this. I’d like to make sure my external backup, Time Machine & photos are accessible from Windows or Linux in the future, so they need to reformatted as ExFAT, right?

If you are talking about a directly-attached backup drive, Time Machine backups should not be stored on an exFAT-formatted drive. APFS or HFS+ (Mac OS Exetended) only, with APFS being the preferred format.

Types of disks you can use with Time Machine on Mac - Apple Support

No matter where you store Time Machine backups, Time Machine is not the backup application to use if your intention is to pick apart those backups using Windows or Linux. A Time Machine backup is best treated as a "sealed box" that should only be accessed via Time Machine – which only runs on Macs.

Carbon Copy Cloner and SuperDuper! are clone backup programs, so if you made backups using one of those, you'd have an easier time picking through the backup on Windows or Linux. You still might want to use APFS or HFS+ for the format of the backup disk. I'm not sure whether certain programs like Photos like having their databases stored on any sort of Windows-formatted volume.