It is usually recommended to disconnect the gryphon before doing anything to/with the electrical system. I would disconnect it and charge the battery, then drive the truck around with it disconnected to make sure the battery has a full charge, then once you are sure the battery is good reconnect the gryphon in the correct way. That should solve any flickering, unless the unit got fried... I hope not, and it shouldn't be, but it is possible.
Good luck
