iMac screen sleeps during boot process, won't wake with trackpad or keyboard input
I'm having a very strange issue with my 2017 iMac 27".
When I attempt to boot as normal, the screen eventually sleeps during the progress bar screen. This is completely normal and expected as I have my computer set to put the monitor to sleep relatively quickly.
What is NOT normal is that it won't wake back up with keyboard or trackpad inputs (I've tried both wired or bluetooth).
Even stranger, the machine does seem to recognize keyboard inputs during the brief period before the monitor goes to sleep. I know this as I am able to boot into recovery mode and reset PRAM via keyboard shortcuts before it sleeps. However, attempting to boot into Safe Mode is not possible as the screen sleeps while I still have SHIFT held down.
I presume that the actual boot process (whether safe or normal) is actually completing without issue, but I am simply unable to see or interact with the login screen.
WHAT I'VE TRIED:
- Reset NVRAM
- Reset PRAM
- Used various combinations of wired devices (i.e. - not a bluetooth issue)
- Performed first aid/repairs on all hard drives via Recovery Mode (Luckily, the cmd-R input is recognized quickly enough to beat the sleep clock) (Also note that input devices work just fine in Recovery Mode whether wired or bluetooth...)
- Rebooting many, many, many times in the hope that it magically cures itself (this did happen once a few weeks ago but resolved itself after a single reboot, so I'd written it off as a fluke)
WHAT I'VE NOT TRIED:
- Reinstalling OS via Recovery Mode (actually attempting this right now - should conclude in a couple hours)
- Restoring from Time Machine back up (doesn't seem like this would do anything)
- Booting in Single User or Verbose Mode (not only am I not smart enough to properly use those modes, but I'm confident that I couldn't get them to boot properly regardless for the same reason that Safe Mode won't work...)
What could be going on? Does it seem like a hardware issue? Something else? Any troubleshooting steps I've missed?
