Firmware Recovery of Wing PCB


Hi all,
I had to update my old Playback wing (2nd generation, but not the new revision) including the IIC PCB update. It went all fine beside the final 10 LCD button panel update:
The tool stated that I went fine, but after the restart, the LCD buttons below the faders are dead and within the Update tool the PCB doesn’t show up at all. I guess that somehow the firmware is corrupted and there was the possibility to write the firmware directly to the PCB via the 6pin connector on the PCB.
In former times I’d simply go to the German Martin Subsidiary which used to have the cable. But I’ve already contacted them: since the workshop is closed, all those tools and cables are gone. Furthermore there’s no official dealer for Martin controls in Germany…
So how can I now recover that stupid PCB?
Thanks for any support!

Best regards