unfortunately, i have removed CPU, and the short clears. think this generally means it's dead/bad cpu. perhaps not all destroyed, but certainly needs CPU reball/replacement. equally strange and disappointing.
I was able to finally fix one by replacing a series of components near the battery charging chip. I also had another one where it was other parts near Power Chip. I think it's completely random in every case. I got 2 of them going again. I wish i had a solid answer for people.
Same issue (15V 0.49A no power no display), but since the switch was a little bent I removed the motherboard and tried reflowing the RAM modules and It worked. I guess there were some soldering cracks and reflowing fixed it.