What cause burned FET driver and FETS on 9920

[tom255]

I put cap to receiver, not to the ESC.
For now i took ESC completly apart. Removed top heatsink from fets and cleaned bottom fets. So total found 12 damaged fets. 2 fets damaged when i removed heatsink. 10 fets burned on the side of +wire and 5 fets on bottom plate and 5 on top plate. 3 fets from 10 had visible burning damage and others had short circuit between Gate and Drain, also found burned resistors, For now i resoldered 7 damaged fets on top plate and seems now OK. on bottom plate is 2 small "GATE" resistors what have 4 resistors in one case, i dont have any idea how i can resold so small things and replace that 2 resistor packs.
Can anyone recommend what to check more? Caps on controller?
Maybe some circuits? Maybe some circuits on driver side?
Lets tel if ESC will work what i can improove? Buy better caps to controller? which ones? Maybe special brand?
Ofcource i will redesign the ESC case for better cooling