I was given a Dell Inspiron 3451 that wouldn’t turn on. Some probing around showed that power is getting onto the motherboard, but none of the switchers that power the CPU would turn on. After some time doing this I noticed that board was getting warm near the HDMI connector, so I then began to focus on closely checking the parts in that area.
What I found was one of the switching power supply controllers had a hole in the package. This can happen when a part overheats, or has to deal with an electrical overstress event (which also turns into overheating and package cracking/venting).
Some more searching found a second suspect part, in this case what appears to be a diode with a pit in the package.
From what I can tell, this traces a path back toward the HDMI port itself.
I haven’t tested all the diodes in that path, but I’m guessing there was an electrical overstress event (ESD or surge) through the HDMI port, which decided to take a path through these parts to GND.
Is this an issue with the design? It’s hard to say for sure, but ideally the energy wouldn’t make its way into major components. Usually there are protection diodes (possibly all the other parts in the top left) that should provide a fast path to the board’s ground plane, but in this case it didn’t turn out well.
Given the damage done, it’s probably not worth attempting to repair, since I don’t know what other parts might also be damaged and this is a low-cost laptop to begin with. Best option in this case is to salvage parts to repair other things.