I was working on someones notebook, symptoms power on then shut off, so after testing all power with a meter everything in the power was working. Tested ram, hd all working. The circles are the main areas of corrosion, bought a new Mother board and now all is working. The owner is so happy this system cost him almost 2000 a few years a go.
Took the p300 apart and to my amazement the dielectric paste Toshiba use caused server corrosion. Some of the transistors fell off with a simple blow. I remember back in my water cooling days, I made the water fountain water cooling system, I had the same issue with corrosion using dielectric paste. Cost me new system.
I read most post on the net with people having power issues. Contacted Toshiba and advised them to stop using dielectric paste. With proof of the cause.
Wanted to mention I am the first to discover this issue no searches mentions this as the main issue with Toshiba notebooks. I just spoke with Tosihba Science lab with live video feeds. They are changing the use of this method.
Edit: If you cant see the corrosion you need to enlarge the image
Edit: All areas of corrosion are in areas that power is being transformed notice how the only parts affected is where they use that stuff. Tosiba has the board now for testing
Your discovery is interesting but inference rests on shaky ground. I would be surprised if this is not a one-off case due to user abuse in ways similar to the one mentioned by Brett928S2 . In my view, either the user is not aware of accidental spillage (the culprit may not have informed the user) or has kept you in dark.