I have found that sometimes the reset button does not seem to react but a combined pressing of the rest plus the on/off slide does. At least it lights the led, and usually it fast shutdown the machine.

i think the reset is a power disconnector. I hope, that pressing it for quite a while will discharge all capacitors in the device. Thats why the display stays put and the device is off. But thats just what i would think.

Could be. In any case, I'd suggest people to try this combination too before calling repair service