Recently my barely year old S2's Rear Mudguard randomly snapped just past the three screws. Had to walk it home as the wires were still intact so it was draped over the wheel. Contacted Hiboy Customer Support with description of the issue and photo of the damage. Got a response within two days apologizing for the inconvenience and asking for the order number. Attached was a PDF for replacing it.
It surprised me in the mail today :) The mudguard is a little thicker than the original and sits slightly higher. There is also a metal plate running almost the length of the mudguard to cover the wires and reinforce the structure. When replacing, keep in mind that if your wires are still intact, you won't need the extra cable they send. There is an extra step with the reinforced mudguard though.
Unscrew the first 4 screws (the end that attaches to the scooter) on the under-plate and gently pry it up. Connect the cable from your scooter to that cable, this is so the tail light has power. Put the screws back into the under-plate. When placing the screws attaching the mudguard to the deck, I found it easiest to start with the trinity screw closest to the deck then the two others. Power up the scooter and click again for the headlight to check the tail light. Place the silicone plugs over the three screws and you're finished! Should take 5-30 minutes depending on your screw driver skills and how well you reconnect that cable.
Thanks again for the quick, quality response!