Three Little Synths - Korg Triton

I have owned this beauty for almost 20 years now. Bought it when it was new and it has definitely seen much better days. I’ve been thinking about refreshing all of the front panel buttons, knobs, and sliders, and finally took it out of its bag for the first time in 5 years. Powered it on, and to my surprise, it still has my sounds! Well, I think it does. This is because it is completely unresponsive to any control panel input. No matter what slider I move, button I push, or knob I twist - the only thing that works is the volume slider and the controls around the stick (including the stick). When I try to use the TouchView it beeps, but does not do much more than that. It is stuck in the one sound that it boots up with. I have not tried changing the patches via MIDI.

Anyone have any idea why this baby is behaving this way and how to fix it? Thanks in advance!