The GEM had decided not to start one morning even though it was plugged in overnight. Turned the key and nothing on the dash. Checked the 12V Aux\battery and it was significantly under the 12V. Eventhough this same battery had been replaced w/in the last year, I still put in a different fully charged battery. The GEM runs but now I have the ‘wrench’ and ‘red triangle’ on the dash gauge. I cycled to see what the fault code is and the only code is 520358:4, but also the outline of the battery pack was flashing and without any of the segments indicating the charge of the pack…it was blank inside the battery outline. The C to the left of the battery outline changed to a 7. This GEM has had no previous service issues and has the original Leoch DTA6224 AGM batteries x8. The battery pack is sitting at 51v measured at the pack. In another msg on this forum, they state 520358 is BMC Thermistor Fault…I don’t know if this is correct or not, could someone pls verify? I removed the battery sensor on the NEG post of the pack and it has 4 pins, two pair of leads. One pair measures 8.8kOhms at ambient temp, when applied heat, this resistance drops consistently and goes back up once heat is removed. The second pair of leads remain open (0ohms) throughout…no effect. Is this normal or could it be defective? Is there another way to test this thermistor? Absent this being the problem, I’m assuming it might be the BMC. IF this is the case, is it just a matter of ordering a new part and have the service tech program it based only off the battery-pack information and maybe the charger, and have them send it to me? I am open to any and all advice/suggestions for this fault code. Paul