My original PCB went bad after two weeks, so I had to order a replacement. I initially thought that it would be an advanced process, but it turned out to be very easy with the proper tools. The only hard part was squeezing it through the front cavity, since other thicker wires occupy it at the same time.
All you have to do is unscrew the fender itself and then several Phillips-head screws. You can then use a hair-dryer or heating gun to temporarily liquify the hot glue that holds the main wire in place and swap out the old PCB with the new one. If you do not have a terminal-removing tool, then you will need a new 5-pin JST-SM connector for the wire pins. The wire color order is Blue, Green, Black, Yellow, Red. Make sure that you put the connector on AFTER you route the main wire through the deck cavities, otherwise you will not be able to get it through.
Put everything back on and you will have a functioning light on your rear fender!