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TitanFlight Li-Ion battery repair

Hey guys, beginner here
I have fair knowledge of electronics but I thought I check with professionals before I do anything so here's the deal.
I have two 7000mAh 4 cell Li-Ion batteries each in 2P4S configuration and I left them connected to their Y lead (parallel lead) after disconnecting them from the power module of a Ranger ex 757-3. For some reason, one of them ended up with 3 overcharged (4.5V) cells and one undercharged cell (0.5V). My guess is that the other battery acted as a charger.
I thought of draining the 3 cells down to a safe voltage (4V) and then using a balance charger to top all the cells up to 4.2V.
I used a voltmeter to identify the leads of each cell on the balance lead and I'm going to drain them one at a time in a little 2212 920kv motor.
Would that fix my battery or is it going to explode in my face?
I appreciate your help and thanks in advance
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Would work I think, but don't use a motor, rather use a lamp or something. also try to use thin wires, so if something shorts out it just burns the wires and not the LiPo.
And please be careful with LiPos, if possible do it outside with a good distance between you and the battery.
What kind of charger do you have? Would likely be easier/safer to put them to storage charge, then slowly charge back up to verify all cells still good if you have a decent smart charger.