Korg DW8000, Mono/Poly, MS-20...

Maybe a brute-force approach would work for you?


Get a copy of the Poly 61 service manual and print the page that shows the main 
digital board schematic.   Take a multimeter and verify the connections on that pcb,
one at a time.   As you check each one, color it with a highlighter.    You can buzz out
the whole board in one evening, I think.   Add wires to restore any connections that 
have been eaten away by the battery leak.


The alternative is to use an oscilloscope to monitor the MCU reading the front panel 
switches and see what's not working.   But maybe you don't have a scope?


Bob