Do you have a manual handy?

I'd check 2 things...

1. What 'mode' are you in? If you are in race mode, there is no reverse. This is off the top of my head, but with the battery plugged in, and the ESC off, press and hold the EZ set button until it starts to flash sequences, it will flash between 1 blink and 3 blinks, I THINK 2 blinks is regular mode (100% fwd, 100% rev)... might be 1... I am pretty sure 3 blinks is training mode.

2. Make sure the TX is calibrated with the ESC - thats also in the manual. Accomplished with the EZ set button as well.