But its probably only a simple fault. The 15v gets as far as a FET, which doesnt switch on. This is driven by a transistor, which doesnt switch on. The base of this goes down a via to somewhere.
By connecting a lab power supply across the battery, I can get the thing to run, but it stops without the battery. Leaving the psu there is fraught, I cant quite come to terms with the idea of imminent explosion.
It seems a shame to chuck it in the skip, the spec is a LOT better than the workshop computer.