Thank you all for the response. There are two issues that I have here:
1) The PSU
It's dead, totally. But with no obvious signs of any malfunction - no blown ICs, leaking caps, no shorts, nothig. I don't know where to start or IF to start, because if the "SMPS green hybrid" is shot, then this is basically just a fancy paperweight. Without the schematic it's very hard to tell. On the primary side - all the caps, filters, rectifier bridge - it's all ok. The rectified line voltage is present as expected, but nothing is happening. I still haven't got time to poke with a scope on the secondary side (i'm too afraid of blowing my working scopes by poking on the primary). The PSU should autostart, according to the manual.
2) What of the scope itself is dead?
I want to power the scope from bench PSUs, I've applied all the required voltages to pins of the cable connecting the PSU and rest of the scope. Got some LEDs light up on the CPU board and the fan starts, but that's it. No CRT, no nothing. I think i'm missing somethng, any ideas?