I DID IT!!
It totally worked
I found an atarimax workbook with a new version of the fat32 loader (20130224) and then loaded that. Selected the updated .bin file from the MYIDE-ONLY#7 file and pressed CTRL+F and it worked. It reflashed the cartridge and I now have something that looks much different. It says "Mr.Atari (c) 2018 BETA" on top of the screen.
Long story short, booting into basic now works

Amazing Sijmen. Thank you very much for your time and effort.