Recurring iMac problem during OS updates: any ideas?

[michaelsaxon]

Hello, I have a loaded up 27" iMac that is the last one from the Intel era. When I do an OS update, it inevitably gets somewhat through the process, turns itself off as to be expected, then the Apple symbol never appears and the power button becomes useless to get it on. I've tried all combinations of resets, power cord removals, etc., to no avail. Last time this happened the Apple Store fixed it in a few days, something to do with reinstalling the bios I think they said. Sadly, it just did it again during another step update. Any ideas or am I stuck bringing it back to them and then not updating from this point forward? Thanks.

 

[Bigwaff]

I have a loaded up 27" iMac that is the last one from the Intel era

So it is 2020 Intel iMac? Model number and more would be helpful here.

Try running Apple Diagnostics. Maybe hardware issue?

Use Apple Diagnostics to test your Mac - Apple Support

Apple Diagnostics, formerly known as Apple Hardware Test, can check your Mac for hardware issues.

support.apple.com