Did the truck roll-over and damage the receiver antenna. The business end is the last 2" and if that gets ground/cut off you will have limited range and issues with servos.
Lipo's swell from either sitting for weeks/months at full charge, running the vehicle past LVC, or using the wrong charger or incorrect settings. You need a cell checker or a charger with a display to see the voltages of each cell in order to determine if the pack is OK.