Blown power circuit in a PC 9821 NA9

Just got this off eBay, a prior owner did a capacitor replacement. There is a short circuit somewhere that is causing it to smoke when you press the power button. Any ideas?

 

I'd pull the caps and start over. Make sure there aren't any bridged solder points from his solder job. If there is a short, I'd be looking for bridged pads first. Then I'd redo the sellers work second

 

The circuit seems to be a buck converter used to power the cpu. On closer inspection I see black ooze. The mosfet may not have failed but more likely some thing on the other side. I won’t get to a soldering iron until Monday. That board needs to come off...

 

Photo of the other side, the 9435 mosfet (Q18) was shorted source to drain as is the FS30 mosfet (Q19)
The soldering job didn’t damage anything, replacing Q18 and Q19 resulted in them blowing again. The diodes are good and the other mosfet pair (Q09, Q10) is good. Any suggestions?