Hi, I dusted off a portable roland PMA-5 wich had of course che "Backup NG" and "Battery low" errors and the internal coin cell battery had developed a small leak which did not spread over. I was confident that changing the battery would had solved completely the issue but in reality only the "battery low" disappeared, i'm still stuck with the "Backup NG" and sure enough when the device is powered off for a while settings are lost. So there must be another problem there, i looked carefully at the pcb and couldn't see any sign of corrosion and caps look fine by a visual inspection, no leakages found.

I tried resetting the device multiple times and putting on a different battery, i checked if voltage was coming through and different points in the PCS were powered by that battery, though i can't know all the parts that expects a voltage and the expected value. Is there any known fault that leads to this problem or anything to check that is worth trying to start desoldering things, given that i could damage something else in the process? Thanks!