Restore on iMac seems to have screwed up everything
iMac late 2015, Catalina
Lately my iMac acted up a bit. When it had been on for a few hours, most of the time idling, it did not shut down. I always had to use the power button.
I decided to restore it according to https://support.apple.com/en-us/HT203981#macos . (restore both MacOS and files). The restore began but informed me that a restore was not possible and I should pick another TimeMachine Backup. I tried a couple of different backups but after a few GB I received the same error message.
Now I am unable to start the iMac. I get a blue screen reminiscent to the Window screen-of-death which basically tells me I am screwed.
Shouldn't there be some safety measure installed that ensures the backup is flawless before the procedure erases the startup disk?
Is there still a way to maybe get the system working again?
iMac 27", macOS 10.15