Xbox one won’t power on, no response.

So I bought this Xbox one s off of somebody on Craigslist. His claim was a power surge caused the internal power supply to quit. I’ve replace the psu but still no response from the Xbox. I started to think that this wasn’t what actually happened so I took everything apart looking for what damage. On the underside of the motherboard I found very small traces of a white residue but nothing that looks serious.

Where do I turn to next in trying to diagnose the issue?