Thanks for the reply!
I managed to downgrade my laptop by removing one of my MX500 SSDs (removed the m.2 one) and using a renamed BIOS File (GL702VM.BIN), a FAT32 flash drive and the CTRL+HOME combo at startup. But this is a pretty hard error, how could this slip QA?:mad:
Also I think my problem with the boot comes from my RAM (Samsung M471A1K43BB0-CPB and Crucial CT8G4SFS824A). Is there any combination that definitely works (16 or 32GB)? I can't find an official QVL for memory....