Just some info to pass down to your tech friend: if the fuse is blown and this is a SMPS (switch mode power supply), chances are the MOSFET and its source resistor are dead too. PWM controller also gets damaged sometimes... if there is one in this SMPS (some designs use oldschool 2-transistor self-oscillating circuit.) That being said, if the SMPS has a "standard" voltage output (i.e. 3.3V, 5V, 12V, 24V, etc.), it might be just cheaper to replace the SMPS module with another one that outputs the same voltage and call it a day. Also, in the case of SMPSes, a blowout on the primary rarely causes damage to the secondary, so the rest of the unit should be fine... though I certainly hope I'm not jinxing it by saying this. 🙁
What's indeed puzzling is why the PSU blew after 2 minutes and not instantly. If the SMPS has a 400V (DC) input cap, then it really should be a "full range" 100-240V AC input -capable. Stuff that's built strictly for 110/120V AC for the USA (and Japan) typically carry 200V (DC) -rated input caps only, as they are much smaller and cheaper, and it makes a lot of sense from a manufacturing standpoint to save on costs with a simple part swap right there. So it looks as if it was built as a universal / full-range SMPS, but then wasn't? Again, really puzzling why the PSU manufacturer would do this.
Relating to this... I recently moved from the USA to Europe and brought a few electronics with me. One of them was a surround sound system rated for 120V AC input only and accordingly has only a 200V DC -rated input cap. Being an SMPS, I swapped it with a 400V cap as a cheap attempt at converting it to European voltage system. However, through careful testing, I have found that this is a no-go in the long term, since the US version of the SMPS also lacks some other components in the snubber circuit, making the main switching MOSFET dissipate 2x more power (i.e. 2x more heat). If left this way, it seems like it could certainly overheat and blow. Mine can run for 5-10 minutes, but gets very hot afterwards, so certainly I have to do a bit more work to make it a proper 230/240V AC conversion. But at least I could observe the PSU was built for 120V AC only. In the case of the Rolland SMPS, we still can't get a clear picture if that was the case or not. Thus I also think the possibility of the PSU blowing due to something else is not out of the question quite yet.
Anyways, hopefully we get an answer to this and hopefully your unit will work again with an inexpensive repair.