- whats the serial number of the truck?
- what is the display showing when this happens?
- what is the actual state of the battery? (not what's showing on the BDI).
- if you have a hydrometer check the SG. (do this only after charging for a true reading on each cell, SG levels are relative to the state of charge of the battery so don't check it when the battery is discharged)
- was it low in water/fluid? is the fluid level ok?

use a VOM and check it unloaded and under a load using hydraulics. How much voltage drop?