What am I supposed to do with my dead MacMini after Montaray killed it?

Restore to Big Sur (select your Time Machine disk when restoring)

My Mac mini 2018 stopped properly using Thunderbolt LG Ultrafine 4K in Monterey while HDMI to a TV was fine. SMC & PRAM reset or Revive and even Restore did not help and I downgraded to Big Sur from a bootable Carbon Copy Cloner backup. Now Big Sur works as usual and I'll try Monterey later after it is updated.

https://discussions.apple.com/thread/253325064

DM88 wrote:

works beautifully with previous MacOS with the same cable etc.

Did Apple support suggest a different cable? That is if a different cable is even available.

What brand, model and year monitor is it?

I had a similar problem and it turned out to be my external HDD. Once I unplugged it from my iMac and rebooted the installation went its merry way. Luckily the HDD was just a backup of a backup, so nothing lost but the installation DID kill the drive. It was working fine before it and now it doesn't even come up on another Mac.

You might be able to use it for a trade in.

Or, you can take it to an Apple store or Authorized Repair Center.

See you other posting on same question

https://discussions.apple.com/thread/253303975?page=1

The first thing before an upgrade is that one must confirm if the hardware is compatible and supports the new software.

Incase it isn't, one must never go for an upgrade. Try connecting with a new display or see if it will revert back.

OR Wait if there is an update and that may solve the problem or you may trade it at apple store.

What are the specifics of the Mac Mini.?

Actually, no, that is not true. When Catalina first came out there were many folks with systems that had an internal hard drive that ran at 5400 RPM. Although Catalina would run, boot times were incredibly long (15 to 20 minutes was not uncommon) and once booted performance was so sluggish that it rendered the system unusable. Apple's advice (and many, many post here in the Catalina section) was to install Catalina on an external SSD. That solution worked wonders. Along with my new MacBook Pro, M1, I also have an Intel iMac (2017) which had Catalina installed on an external SSD, and was recently upgraded to Big Sur.

The fact that Apple is restoring systems that have been bricked by a failed Monterey upgrade tells me that they have identified an issue and have addressed it.

Two cents worth and IMHO.

Often times, the issues are really self inflicted by the level of modifications, outdated extensions, cr*ware installed and lastly, failing to perform the due diligence before attempting a new or newer version of macOS.

That and not having an Exit / Recovery Plan if the installation goes south or sideways.

Yes, Apple is not perfect and does have room for improvement, though, the last really bad experience I had was moving from Tiger to Leopard.

MargeHomer wrote:

Actually, no, that is not true. When Catalina first came out there were many folks with systems that had an internal hard drive that ran at 5400 RPM. Although Catalina would run, boot times were incredibly long (15 to 20 minutes was not uncommon) and once booted performance was so sluggish that it rendered the system unusable. Apple's advice (and many, many post here in the Catalina section) was to install Catalina on an external SSD. That solution worked wonders. Along with my new MacBook Pro, M1, I also have an Intel iMac (2017) which had Catalina installed on an external SSD, and was recently upgraded to Big Sur.

The fact that Apple is restoring systems that have been bricked by a failed Monterey upgrade tells me that they have identified an issue and have addressed it.

Come back to the original premise - Often times, the issues are really self inflicted by the level of modifications, outdated extensions, cr*ware installed and lastly, failing to perform the due diligence before attempting a new or newer version of macOS.

That and not having an Exit / Recovery Plan if the installation goes south or sideways.

Yes, Apple is not perfect and does have room for improvement, though, the last really bad experience I had was moving from Tiger to Leopard.

It is doubtful the Monterey is the source of killing the machine. If there was a hardware failure - that is a different matter.

What exactly happened when upgrading from what pervious version of macOS to Monterey ?

Is there any After-Market Hardware involved on this machine ?

I fail to understand why people comment the way they do sometimes.

Neither can I.

You stated you Mini was dead, but it really wasn't. Did you intend to be hyperbolic? That's what I assumed, and I was right.