Digital Side CAR

On with the repairs again for the digital side car. Major design flaw with this board! there is suppose to be a fuse to protect the input, it is on the schematic but not on the board. There should be a PTC fuse CB1 it there to protect Q1, but it did not on this board and a reverse battery polarity blew the SH!T out of it, because there is an internal diode, if the diode was not there it probably would have been fine since the FET only turns on when VBATT is the correct polarity, I replaced it with a through hole MOSFET without a internal diode. I'm so surprised this design got out to the kids. I did find a CB2 but it connect to another part of the circuit.