About a month ago, I successfully installed Ubuntu MATE 20.04 on my Raspberry Pi 4B by flashing it into the card. Then I flashed Ubuntu MATE 22.04 and now I’m trying to go back to 20.04 but, no matter what I try, I get the “this board requires newer software” screen. It says the start4x.elf and fixup4x.dat are not compatible. I have tried to replace those with the newer ones from the Raspberry Pi firmware GitHub repository, I’ve also tried replacing all the start*.elf and fixup*.dat files, but then the installer crashes on startup (apparently when setting up the keyboard), and even the bootcode and the entire boot partition. I’ve tried eeproms from 2024, 2023, 2022 and 2020. The first and last just give me a black screen, and the rest give me the aforementioned error. Normal Ubuntu 20.04 doesn't work either. I’m using the same SD card, same charger, same everything as before, but it doesn’t work anymore!
Here is an image of my screen right now:
