A friend had this same problem. I don't know what caused it. But he lost one side going one direction.
Either your SD card is corrupted and is making the IBU whacky , which if everything else works, probably not, or you killed something.
You should contact Ian the dealer in the UK that sells them and tell him whats wrong. You probably are gong to have to send it back for repair. It will take a long time.
Sorry, but that is the most likely issue. But... he might have more input for you and some tests you can do.
I warn you, the new ultimate boards, the blue ones, have a inertia setting built into them you cannot turn off. It makes the tank very sluggish and unresponsive to drive. I bought one and hate it and wont use them. They eventually plan to do a firmware update but have not yet. IMHO they new boards are unusable if you plan to IR battle or drive around obstacles.