An ERROR '004' code displayed on the display indicates throttle fault.
You can proceed as follows:
Firstly, unplug the throttle cable to see if there is still pedal assist function at this time. Then plug in the throttle cable and unplug two brake cables to see if there is still pedal assist function at this time.
When throttle cable or two brake cables is unplugged, the pedal assist function still works at that time, which means that that part (throttle or brake cables) caused error code 004 and that the part needs to be replaced to solve the problem.
If both the throttle and brake cables are unplugged, the pedal assist function not work at that time, it should be due to a problem with the controller or integrated mainline, and it needs to be replaced.
For further assistance, please be sure about the cases listed above and reach the SOHAMO support team at: firstname.lastname@example.org