Hallo und herzlich willkommen im Forum !
Regarding the issue on your Migatronic control board: when MOSFETs fail with a short-circuit, they often feed the voltage on the source/drain circuit to the gate, and this can destroy the gate drive logic. You may be able to confirm that the failed SOT3 item is a gate drive transistor by tracing the track from the gate of one of the MOSFETs. There may be another intact drive transistor for the other MOSFET ?