I think you will need the manual in front of you, but the short of it is that you can use the DRS switch to reset everything to 'default,. and to properly set up all the options.
1 caveat, make sure the battery is good and well charged before you get there. this unit has a lower speed setup that happens when the available battery amps goes too low, while voltage is still OK, preventing a too small battery from being used when working, but allowing a smaller battery pack to be used moving the truck before delivery and matching with its permanent battery.