The motor overload error is most likely the PTC connection in one of the motors.
A physical jamming of an axis or any movement anomaly will report a servo Error.
You can trace the PTC connections at the power cable socket at the base of the robot. C1 and C3 connection is for Axis 1. C4 and C5 is axis 2, C6 and C7 is axis 3, C8 and C9 is axis 4, C10 and C11 is axis 5 and C12 and C2 is axis 6. You should have continuity between C1 and C2 as all the PTCs are connected in series.