so this has been driving me crazy for like three days. one of the motors on my quad just randomly spins up for half a second and then stops. happens when its just sitting on the bench powered up, props off obviously. the FC is armed but im not touching anything. its always the same motor, back right corner.

i swapped the motor to a different ESC pad and the problem followed it so i thought ok its the motor, but then i put a different motor on that same pad and same thing happened. so now im not sure if its the ESC channel, the wiring to that corner, or something weird in betaflight. i checked my motor outputs in betaflight and everything looks normal in the motor tab when i manually spin them. running Bluejay on a 45a 4in1 and the firmware is current. dont even know what else to check at this point

have you checked your solder joints on that corner of the 4in1? like physically looked with a loupe or good light? i had almost the exact same issue a while back and it turned out one of my motor phase wires had a cold joint that was making intermittent contact. the motor would get a random signal from basically electrical noise and just twitch. reflowed all three phase connections on that motor and never saw it again.

could also be a grounding issue tbh. if your ESC ground isn't solid back to the PDB or the capacitor leg is dodgy you can get weird behavior on one channel while the others are fine. also worth checking if you have any ESC telemetry weird readings in betaflight for that specific motor ? sometimes Bluejay will log desyncs which might point to whats going on. also what FC are you running, some of them have had bugs with certain motor output pins acting up