Don't take this the wrong way, but if your soldering skills are weak, you need to check down at the board on the RS where the solder posts attach and make sure you don't have any of the motor phases bridged.

If there's absolutely nothing visible that could short out two motor phases, clean it anyway with a toothbrush and some denatured alcohol. "Nothing really there" doesn't count, anything that can make any kind of electrical connection between motor phases will cause that error code, including tire sauce, certain kinds of dirt, solder flux, etc.

If that all checks out and you still have the error code, pull the back plate off your motor and make sure the phase plates are also not touching or electrically connected in any way. Sloppy soldering can drip solder inside the motor can bridge 2 motor phases. Also take the chance to take a look at the color of the windings. They should be a fairly bright red or copper color. If they're dark red, or black, it could be the motor itself.

If everything above checks out, try disconnecting the sensor wire and see if the error code stays the same.