A few years ago, I figured out the main source for motors and ports on the brain dying, but stopped competing shortly after and forgot to share it publicly. It always confused me how certain combinations of wires and ports gave a good connection, but other wires gave a flashing red light on the motor, or no light at all. The source of this problem is the pins on the female 4P4C connector getting bent in over time and not making consistent contact with the cable. If a cable is crimped slightly differently with the pins sticking out more, then it will make consistent contact despite the female connector being bent. By fixing all the female connectors, then all cables will make consistent contact and revive the dead ports or motors.
To lift the pins back up, I just used a bent paperclip but a better solution would be using a dental pick. Be careful not to bend the pins sideways while lifting them up.
I’m not sure if this fix is common knowledge but it should be, considering all the money that could be saved from not throwing out perfectly good motors and brains.
