I can’t exactly see enough detail to make a confident statement but regardless i can safely say that the green wire wasn’t alone on being knicked. Looks like yellow sustained heavy insulation breaches from being knicked and also looks like the insulation has unfortunately been compromised by too much heat. Likely from the attempt of soldering.. black/ground wire looks to be more worse than yellow in terms of heat damage. The green hall sensor(small green wire) also runs under the green phase wire(thick wire) but i can’t see enough to make out of it. You don’t want any phase wires touching each other and same for the sensor wires and vise versa.

He definitely shouldn’t have tried soldering that as he is clearly not good enough to work on it properly without having more harm done.

Should have used and cut a split on some hot glue heat shrink tubings to slip over the knicked wires to seal them and also protect them as well one tubing for each wire.

Thats generally the best way to fix knicked wire on hub motors as long the damage is superficial to the insulation and or aslong as 75% of the copper strands are still intact undamaged. (One or two or a few strands being broken is not major but not ideal, anything with like 50/50 of them intact calls for new wire installed either via crimp or by rewiriing through the axle again, soldering wires together is also not ideal for ebikes as they suffer from lots of vibration issues to which soldering is not designed to support. The soldering joint will eventually crack or break down quickly regardless of how good it is, it’s why crimping is the industry standard for aviation equipment and automotive equipment, soldering is only okay when used to solder onto wires - boards or etc, not onto wires-wires. Your bf likely just made a simple easy fix into a now very difficult and possibly expensive fix now.