Is this a 2010-era with Valence Batteries or a 2012-era with A123 batteries?
If it is the 2012 with A123 batteries, the most important thing you'll need is a PCAN USB adapter so that you see what's going on with the individual battery levels. The official adapter is $225 and it is called the "IPEH-002021", but I found a knockoff for $55. I bought two of the knockoff and can confirm they both work fine, but the power cuts out on one of them if I wiggle the USB. For the price difference, I'm not complaining. Here's the link anyway, they ship from China so it might take a few weeks:
55.8US $ |Replace PEAK PCAN USB IPEH 002021 IPEH 002022 PCAN View|Contactors| - AliExpress
If any individual battery cells are below 2.5v, the entire truck will refuse to drive or charge. To bring up the voltage I know three methods, with varying levels of danger and expense.