Prophet '08 PE - Presets aren't switching

[odd meter]

Hello.

Maybe the issue has been discussed already, but it's annoying AF and I was off forums for too long... Couldn't find the solution quickly.

My Prophet '08 PE is rarely used, and the last time I turn it on, encoders went wild (known issue).
Tried to rotate them both ways without saving values, but didn't turn the machine off.
Re-calibrated the voices (just for the future tasks - unrelated).

After that (possibly not related as well) it has stuck at one preset.
Some could say, I overwrote all the slots with one value... but after any restart, starting preset value is random.

E.g.
ON > A1 "preset1" > switching > A50 "preset1" > switching > B100 "preset1" > OFF
ON > A1 "preset20" > switching > A30 "preset20" > switching > B60 "preset20" > OFF
ON > A1 "preset70" > switching > A90 "preset70" > switching > B112 "preset70" > OFF

So it always displays one random preset it booted with.
Have you faced a similar issue?

[odd meter]

An update: audio outs are also mute.
MIDI is working though. Internal cables are in place.