Dreamshell suddenly stopped working

[Elgor4uk]

1. If the original BIOS chip has the 12th pin removed, then the screen will be black when booting, because the BIOS will not boot. There are exceptions when the original BIOS can boot with the 12th pin removed:
If an additional BIOS chip is installed on top + a switch is installed between the custom and original BIOS. And even if the original BIOS has the 12th pin removed, it can still be booted by disabling the custom one. However, it does not work with all GDroms. Tested and loaded the BIOS on NTSC-J VA0, when the original BIOS has the 12th pin removed.

2. You can restore the 12th pin of the original BIOS. You need to cut off the stone case a little, near the removed 12th pin. A sharp knife + a very small file + cleaning with alcohol helped me. Solder a very, very thin wire the size of a hair to this small cleaned area.

3. In vain you deleted the custom BIOS after an unsuccessful attempt. You should have asked for help on this forum and looked for a solution. I suppose that your unsuccessful piggyback method bios mod was in the incomplete soldering of certain pins. I suppose that the FatFs 5 error is due to incorrect soldering of pin 23.