My machine is a HP ProDesk 400 G4 SFF running Ubuntu Server 20.04.
It was running just fine with the original Intel i5-6500 CPU, but upon upgrading to an i7-6700 the system will no longer boot.
I’ve tried entering rescue mode and emergency mode, but neither of them will actually boot the system. Any ideas?
EDIT: I’m unable to boot from install media on a USB drive either. Here is a screenshot of a failed boot: