You are quite correct, fault code 25.
Right motor open, usually brush problem, upon start up the brush contact through commutator is bad, they get really dirty inside, you can strip down motor, clean
Comm, and blow out, but it will happen again, and steer funny in that direction.
If you push the drive button to push, and physically move truck so brushes are on a different part of the comm, it may start up.
New brushes can help, but have found that harder compound brushes specifically made to order, and bedded in properly, will give best results.
Good luck