No access external drive T5

are you using any of samsung's preloaded software on the drive (or installed such software yourself) that supposedly makes the drive "Mac ready"? if yes, that could be the cause of your issue. when you use software from just about any manufacturer for their storage device you run the risk of that same software not being compatible with macOS updates / upgrades. it can cause the software to stop working. at best this will cause you a headache. at worst it can render your data inaccessible. it is always best to use disk utility to erase and format a drive before use to remove any preloaded software.

if you are using such software, i think your options are somewhat limited. 

you may want to contact Samsung and see if there is an update for their software.

alternatively, if you have a backup you can revert your macOS to the version of macOS that the drive was working on and transfer your data to another storage device and then erase and format the Samsung device before putting it back into service.

please see Erase and reformat a storage device in Disk Utility on Mac - Apple Support.

Sorry to hear you're having trouble with your Samsung T5 on the Mac mini M2. This is a common issue with external SSDs on newer Macs and there are a few things you can try.

First, check if the drive shows up at all. Go to Apple menu > About This Mac > System Report > USB (or Thunderbolt/USB4) and see if the T5 is listed there. If it appears in System Report but not on the desktop, it might be a formatting or permission issue.

Second, open Disk Utility (Applications > Utilities > Disk Utility) and check if the drive appears in the sidebar. If you can see it but it's grayed out, try clicking Mount. If you see the drive but it's unmounted or has errors, you may need to run First Aid on it.

Third, try a different cable and port. The Samsung T5 uses USB-C, so make sure you're using a good quality cable. Sometimes swapping to a different Thunderbolt/USB-C port on the Mac mini can resolve connection issues. Also try disconnecting any other USB devices to rule out a power issue.

Fourth, check if the drive is formatted as APFS or Mac OS Extended. Samsung drives often come pre-formatted as exFAT or NTFS. You can reformat it in Disk Utility, but make sure to back up your data first since reformatting erases everything.

If none of these steps work, it's worth contacting Samsung support to see if there's a firmware update for the T5, or reaching out to Apple Support at getsupport.apple.com for hardware-level diagnostics.

Hope you can get this sorted out!