Battery, charger and turtle mode problems

I just picked up a 2013 gem E4. It has new batteries and the charger is not working correctly, I charged the batteries with large car charger. The battery gage on the cart says they never charged? And it stays in turtle mode. I also looked at the charger on the cart and it first blinked twice and I looked again and it just a steady blink? I have no idea if the batteries were installed correctly but I did change the cable to each one because they were poorly done.
Any help will be appreciated.

Car will stay in turtle mode until it completes a charge cycle.
Count the blinks for an error code.
1 is temperature sensor.
2 is low (or high) battery.

Thank you I will give that a try tonight. Can you tell me where the temp sensor is located? I also noticed two wires in the main harness coming fro the front back to the batteries that are not hooked up? They are hot too? both are yellow and I think they one has a blue stripe and the other I believe has a brown stripe??

Yes, that’s the temp. sensor. It should be under one of the battery terminal bolts. It looks like a big wire lug.