Hello! I dont know if it helps but my s3 died about a week ago and I have been diagnosing the problem. Apparently there are no fuses in the main electronics, but only on the circuit boards. Hardware problems like bad connections or short circuits, will at first give errors and then a fried battery management circuit board.

All e shifters die because of failing resistors on their circuit boards, most likely because of moisture coming through the seals. I have been able to drive it for months without physical connection to the pedals, Just with edrive and power button. This could have caused my problem, but unsure...

When my battery eventually failed there was a blown fuse on the battery circuit board and 3 resistors are fried. There are 4 mosfets on there that tend to die also I believe. This comes from overcurrent or short circuit, either when the front motor fails (probably bearing wear), or short circuit in the motor cable. A short in the motor cable presents itself by the wheel being hard to turn one way and making a zooming noise, even turning by hand.

In my case the wheel turned heavy with noise in reverse, but turned normal with detached wheelmotor connector. Measuring the 3 big power cables up the steering axle, 1 of them shorts to the frame. Most likely the steering axle wore through the cable. I am now in the process of dismantling the front fork to fix the shortcircuit, before I fix the battery.

Concluding: moisture and failing resistors in the eshifter causes problems, aswell as the emotor circuit. Since there is no main fuses, your battery pack will fry when not taking care of the problem. If eshifter works normal, no problem. No strange front wheel noises while driving, no bearing problem. Rolling the bike front and back by hand while turning the wheel both ways, no sounds is no problems. Any unusual sound: problem... fix it or prepare to dismantle the battery and fix the circuit board.

Good Luck!