I, want some help, troubleshooting a 30H error issue I have with my Bafang, 250w motor.

I have done, and ruled out the following,
++ I have checked all of the wiring, and it all seems ok.
++It cant be the display, as, when I connect that USB thingy to my laptop, the laptop is not getting any data from the motor, where as it did work before the 30H.

I have purchased one of those lighting extension kits, and was about to plug in a completed set for a test run when I detected the problem. How touchy is Bafang to this normally?

The only troubleshooting tool I have is, the USB-Laptop connection, of which in effect, replaces the bafang-display.

When I do open up the controller, is there anything I can fix myself, such as replace a fuse?

There is no possible way for me to determine if its a pin connection problem really.