Really sorry to hear of your probs, Krotoff. Sounds like a hardware problem, so contact Access directly and they will be able to advise you further.
http://access-music.de/contactus.php4
You did install the latest OS for the Indigo (OS 4.90 Build 050)?
You could always perhaps try flashing the BIOS again.
Sometimes my Indigo locks up the same as yours, but this is often when I have it hooked up to other synths via MIDI and they sent corrupt or unsupported MIDI data to the Indigo.