RC Car Controller Board Diagnostics

I'm an electrical engineer, but my I deal with 120VAC and up, and every now and then I deal with microcontrollers as a hobby. Remote controllers are out of my knowledge, but I my nephews RC truck stopped steering and I thought I could help. I tested the motor, and the potentiometer which provided the position feedback, and then I tested the out puts at the board. The drive motor was getting a constant -9.6VDC no matter whether I went left our right, and the PWM was not changing whether I steered full or partial. I started thinking it was the control chips, an Amtek AM2837, or the voltage regulator, 6209A. At some point during my troubleshooting, I must have shorted something out because now the receiver and transmitter are not connecting.

Could someone point me in a direction for troubleshooting the receiver/transmitter circuit? I have an O-scope, power supply, and multimeter. I can upload pictures of the board too.