markstos wrote:It started with a sudden loss of power.
You missed the obvious troubleshooting clue, "sudden loss of power with battery & power supply connected" .... this indicates
a faulty power regulator diode on the mother board... ( after overheating cpu is excluded )which any electronics tech (real tech, with voltmeters, osicilliscopes, ect)
can check using a common volt meter, by simply attaching test leads to the voltage diode(s) and booting up, watching the voltage
change on the diode, it will drop from full voltage (5vdc or 12vdc depending on the diode) to zero quickly and poof you got a dead unit
agian, after that bad diode cools off..its ok till it heats up again ( which usually takes about 5 seconds ) simple job to find compatable
replacement diode and unsolder it and resolder new one.. then retest, if happens again then test the remaining couple of diodes to
find the other bad one and fix it. (good diode will show full voltage even as unit goes dead so good and bad diodes are easy to spot)
Lastly...if the diodes are all fixed, and you have some bizzare voltage type issues, then some big caps got fried...(they can be replaced too , usually they show bulging, leaking, exploded..burned..) this is all indicative
of a motherboard that got hit by lightening or power surge... the diodes and caps are protective of the motherboard.. so fixing them
on the repair bench is a simple job for a real electronics tech... but might cost as much to pay them for an hour of work and parts than to buy good mother board..