Toms_view wrote:
What does that mean and what can I do. BigSur installed only. No other hardware on it. Should I go back to macOS Catalina?
I reinstalled MacOS Catallina via restore. (Command + Option + R) Then upgraded to Big Sur 11.1. It's just Big Sur on the MacBook. The error only occurred under BigSur. But that several times.
machine checks (MCA) are hardware or very low level software or firmware. No matter you are stuck. Full stop.
If you can go back to Catalina than sure why not... otherwise you are dead in the water as it stands, and contacting Apple as posted above is the option if you want to sort through the issue, pending some update to correct the installer.
We have already seen issues with the 13" 2013 & 2014 MBP and macOS Big Sur.
I suspect an incompatibility in the new macOS and firmware on your 12" Macbook
Revert to previous macOS
https://support.apple.com/en-za/guide/mac-help/mh15216/10.15/mac/10.15
How To Downgrade macOS Big Sur To Catalina Or Older ...
https://www.macworld.co.uk/how-to/downgrade-macos-3581872/