Alesis QS 7.1 several keys play multiple notes

I replaced the battery but now several keys play multiple notes.
User bank would not save beyond power recycle. The battery was faulty so I soldered a replacement part onto the main board. User bank mods store fine now but several keys produce the sound for a few keys being pressed simultaneously. I rechecked the solder joints and they are clean. The faulty keys follow a pattern throughout from the lowest ascending from C G# E. I’m wondering if maybe one of the ribbon cables are faulty or what. I did try a factory reset pressing 0 and 3 while powering on to no avail.
Any assistance would be greatly appreciated.