Dreamshell suddenly stopped working

[DreamBol]

Hi, I have 1999 Sega Dreamcast VA1 console from PAL region. I have installed ATA cable to it's GD-ROM and could boot Dreamshell from externall HDD using Dreamshell boot CD. But then I wanted to install dual bios mod using piggyback method, I have followed steps from this tutorial:
https://web.archive.org/web/202304281738...free-bios/

I was able to switch between original bios and uprogrammed chip using switch, but I couldn't boot from HDD. Dreamshell boot loader sometimes detected HDD correctly and opened boot selection menu other times it shows FatFs 5 error. I have tried to boot using SD card which doesn't work. I have tried to remove ATA cable after that Dreamshell boot loader started to stuck at searching for G1 ATA devices... . Then I have removed additional bios chip leaving only original bios, I have broken a 12 pin of original BIOS IC but console loaded BIOS without problems.

Out of curiosity I have soldered ATA cable directly to motherboard but it doesn't changed anything. Then I have screwed everything together and since then console gives no AV signal output.

What could caused such issues? I won't be able to check the console for two weeks but I am searching for any suggestions.