Ensoniq DP/4 boot problem

[vesalaasanen]

I have a malfunctioning DP/4. It says unexpected event message 75 in the boot if the unit has not been powered for a while. Then it works for about 5 seconds and freezes. If you power cycle the unit it goes directly to the display/keypad test. All the OS version is 1.15. I tested to reinitialize, system reset sequence, and hard reset.

 

[Khron]

https://groupdiy.com/threads/ensoniq-dp-4-cap-leakage-corrosion.78087/
Also, do those things have any sort of backup battery that might've kicked the bucket? I seem to recall having read they do.