This video walks you through adding a balancer and top balancing the cells. This should sort out these batteries and make them work again!
0:00 Intro
0:56 Opening the Case
5:10 Checking the state of the Cells before charging
6:13 Top Balancing using a Benchtop Power Supply
10:29 Lifepo4 Cells and they're relationship between voltage and SOC
12:24 Installing the Balancer and Switch
20:02 Powering up the balancer and checking it's working
21:50 Finishing the Top Balancing with the balancer and power supply
23:55 Result of balancing and top balancing
25:26 Refitting the case and screwing it closed
26:33 Conclusion
High Temperature Battery Tape: www.amazon.co.uk/dp/B0BVFHZQYP?psc=1&ref=ppx_yo2ov_dt_b_product_details
5.5a BMS 4s Active Balancer Board with protective case
www.amazon.co.uk/dp/B0CKHCGSNT?psc=1&ref=ppx_yo2ov_dt_b_product_details
DPDT Latching Switch
www.amazon.co.uk/dp/B09Z61114Y?psc=1&ref=ppx_yo2ov_dt_b_product_details
5a 30v Benchtop Power supply
www.amazon.co.uk/dp/B0BTDH41YH?psc=1&ref=ppx_yo2ov_dt_b_product_details
22awg single core wire
www.ebay.co.uk/itm/145085844929?var=444283791018
Crimp Terminals
www.amazon.co.uk/Taiss-Connector-Assortment-Insulating-Electrical/dp/B0BYZ4FQFB/ref=sr_1_2_sspa?
Heat Shrink Tubing
www.amazon.co.uk/Eventronic-ET1002-Shrink-Electric-Insulation/dp/B071D7LJ31/ref=sr_1_5
Self Tapping Metal Screws
www.amazon.co.uk/FandWay-Drilling-Phillips-Self-Tapping-Windows/dp/B09MH5MKWL/ref=sr_1_6?th=1