[suicideneil]

Start from scratch:

1) tx settings all to normal, nothing reversed.
2) same with the esc settings, nothing reversed on the motor direction settings.
3) set the throttle for 50% reverse power, 100% forwards- the truck should stop when you hit the brakes, not go into reverse after slowing down or stopping ( have to release the throttle trigger to neutral before engaging reverse).
4) test it- if there are no brakes when you go forwards to reverse, the you have the throttle channel setting wrong, and it needs to be reversed on the tx. You will need to recalibrate the esc to the tx after you reverse the throttle.

If the truck runs backwards, but the brakes work fine when going from reverse to forwards ( will slow down to a stop, then go forwards after releasing the throttle to neutral first ), then you just need to switch 2 motor wires around and it should work fine from that point.

I would still contact hobbyking about the lipo and explain that one cell has died after one run- they do have customer support so even if it takes weeks I wouldnt just write-off the pack. It can be reconfigured, but that does require a skilled hand to do it carefully.