My son just bought a polaris 850 the seller told him it had no spark and computer was bad. When he got it home we confirmed no spark but it would turn over. we took it to local shop where they hooked a laptop up to it when trying to start it it would try and start but backfire. Then it went to not turning over at all with no brake light or front lights, dash still comes on fuel level blinks. We checked all fuses and relays Computer was cleared at local shop. Any help from anyone that may have the same issue would be greatly appreciated.