Why did the power mosfets burn up on two FC boards?

[joemafioso]

My original FC board fried the power chips so I replaced the whole FC with a different board and the same thing happened the two power chips fried. I might also add that I also was getting voltage critically low immediately and I also bought two brand new batteries and threw away the old ones. The GUI shows everything good and 12 volts with a fully charged battery. Obviously something is causing this issue and that's what I'm trying to figure out. I don't know what else to do. The badly burnt one is the original the other one is the replacement. It doesn't look bad at all but when I turn the drone off the lights still stay on just like the first time it happened, I have to take the battery out to fully shut it down.

 

[WTFDproject]

Did anything happen between the last good flight and the first incident of blown chips? Things like crash damage, any maintenance related to opening the shell, water in the motors, replacing ESCs, or anything else you can think of?

Have you checked for a short between the positive and negative side of the power connections going towards the motors? If you don't see a short with the shell off, look very closely at each pair of motor wires to see if any were crushed last time the shell was assembled. Also check the power and ground wires to the camera.