Wild thumper not responing - trouble shooting

Hello all, 

I am a beginner in Arduino, Electronics and Robotics - programming i can do. My Wild Thumper started to behaving weird. I fear that I have destroyed it, but I would like to hear your input.

Here is my setup: 

Here are the symptoms: 

  1. In the beginning, all was good. Except one thing: Left/right steering was opporsite to the RC directions. I had a hard time correcting it. 
  2. A few days ago, the Thumper started reacting stangely to the RC. Nothing happens when i try to steer. Except backwards - It will start with a few seconds delay. Nothing is happening in other directions.
  3. Code is still running on the controller.  
  4. I monitored the RC pulses throug Serial.print statements. They are normal. 
  5. Now, the led is not turning on when I connect a power cable (12V 2A). 
  6. The board is still turning on and at least running the code, using the battery. 
  7. Both fuses seem to be intact. 
  8. No visible problems on the board - no damaged soldering, no burn marks. But as stated, I am a beginner, so I am not sure, if I know what to look for. 
  9. I have tried to move the RC to other pins. No luck.
  10. Problems are observed in the original Wild Thumper code, as well as my own altered version. 

Can anybody tell me what is going on here? Is the controller dead, or is there still hope? 

Hints to further troubleshooting, would be greatly appreciated. I live in Ghana, where there are no Arduino shops around, and webshopping is not really an option, so it would be really nice, if I could get the controller up and running again.