Think will not run showing trouble code 42 on cluster

Hi I just got a 2002 think neighbor. New gel 100mah batteries were installed. Ran great for about a week and after last charge cart will not go. Cluster lights fine and all fuses seem to check out. I checked for trouble codes and got a 42 code. When you push go pedal down I get a flashing wrench and the battery symbol shows blank. All 6 batteries are at 12.6v and total output is 72.8 volts. Any ideas if what’s wrong.

You might try Scott. He is extremely knowledgeable about Ford Think NEV’s.