Mac Studio won't boot, light blinks once
My M2 Max Mac Studio has been shutting down of late when left asleep. Two days ago, when I tried to turn it back on, it would not boot. The light would blink, but nothing would happen. I kept trying, and eventually it booted, not sure why. I entered Recovery, tested the discs and there didn't appear to be any problem there. The system could not do a recovery from my Time Machine backup so I opted to reinstall the OS (15.3.1). That took a long, long time but eventually worked and the computer restarted, all was well, data intact.
However, I shut it down at the end of the day and the next morning it would not boot. All it would do was blink its power light when I pressed it. There was no life in it at all. I left it overnight, and this morning it booted. Again I tested the drives. There were a number of errors relating to resource forks, all related to Time Machine. As the Time Machine drive was not connected at the time, it felt safe to ignore these for now. Other than that the disks looked fine. I once again reinstalled the OS. Once again, this has worked, and it is fully operational. I'm typing this message on the Mac Studio.
But... what happens next? Are there any tests I can run which might reveal the cause of the problem?
I don't know if the machine will boot again after a shutdown. It is clearly not reliable and something is wrong somewhere.
I've searched online and there are two possible hardware fixes: replace the motherboard, which doesn't seem to work for most people; or replace the PSU (power supply unit), which does work for some. All of that is anecdotal, of course.
Are there tests that I can run to find out what is causing this power / boot issue?
The machine is out of warranty, by the way. It's barely 18 months old, but replacing the motherboard would be very expensive. It's probably not worth doing and better to save the money for an M4 Mac Studio, or even a Mac Mini.
Any help or advice is appreciated.
Mac Studio, macOS 15.3