Just blew a fuse most likely....
The large/small tamiya's have different polarity
On I think small tamiya the red wire is a round plug connector and the black is square
On large tamiya it's ar$e about face, red wire is square and black wire is round connector...
Or something like that, some converters especially off fleabay don't swap the polarity correctly
So you need to unpick the adapters and swap them over
What it sounds like to me, you got it wired up in reverse polarity but the AR latch stopped gun cycling in reverse but this locking warmed the wires & blew the fuse
Sort it out on polarity and fund should be ok if all goes ok