Hi, a few weeks ago I received an IBM 6275 in perfect condition. Good caps, clean motherboard, just a little dusty here and there.

I updated the BIOS SUCCESSFULLY, and put it away, waiting to figure out what to do with it. Today, after 1 month more or less, I wanted to try it out and improve the CPU by running some tests, but suddenly I got this error, which doesn't go away. I don't understand what happened since the PC was left untouched since yesterday.

1) The keyboard lights up, and if I repeatedly spam press F1 to enter the BIOS, i get the BEEP from the speaker ( so the command is recognized ) but still won't let me inside the BIOS, and it continues booting, only to stop at the same error code
2) The underscore below the error code is flashing, so i suppose the PC is not completely frozen in error, but that's it.
3) I also tried to start the recovery mode ( by changing the 5th jumper ), starting the PC with the BIOS floppy disk, the PC starts and read the floppy disk, but again with the usual boot which leads at the same error ( so i assume the flashing don't even start somehow )

As last attempt i tried to change CPU with a Pentium 2, then Pentium 3 with various speed but it freezes with the same error at the same spot. Any idea ?