New to me 2016 yamaha g29

[TruthHurts21]

So i just bought another yamaha g29. 2016 model. Got it for a fair price. Just needs batteries so he said. They were completely dead and stored. One had less than a volt.I managed to charge the pack up but after charging overnight resting voltage was 49.9. I did get the cart to move bit its jerky and weird noise coming from motor. High pitch noise that goes up and down. The noise stays steady when i press the pedal. Looks like it has aftermarket fsip sx controller. When i was riding it the pack voltage went down to 44. Would that cause jerkiness? I would assume so. Im hoping to score on some used like new batteries but might just go new. Also something i noticed. When i was trying to operate last night before battery charger was done i noticed solenoid was getting very warm just sitting there. It would not move at that point. I guess i need to get batteries first to eliminate that. I just wasnt sure if i should test other items and i wanted to see if anyone could link to a trouble shooting guide. Is it all covered in the service manual?

[TruthHurts21]

A little more info. It takes a few presses of the pedal for it to move sometimes it won't. I have to press the pedal more than halfway down then it lurches forward. The weird modulated noise is defiantely coming from the motor. If i tap on it it kinda changes tone and sometimes it will activate solenoid once or just keep activating it on off on off. Even though this battery pack is 6 years old it seems to be holding voltage. But would bad batteries cause this behavior? Figured it would just run slower or not have enough power.