Of course, it is best if you can find someone local who is knowledgeable and has the skill to fully inspect, troubleshoot and/or repair your battery. However, if you cannot find them, there are companies that will accept batteries by mail. Whether finding someone locally or online, make sure you check their reviews, costs, and any warranty they offer. Some of them, while costly, are cheaper than a new battery and some provide a guarantee or warranty.

Alternatively, you can check for local experienced people on Craigslist. Of course, you must determine if they will be able to help you and have the proper skills.

The required skill may require some or all of the items listed below::
Proper knowledge of Electrical and battery safety.

Wire crimping connectors

Selecting proper gauge wire (thickness/diameter)

Properly charging individual cells or replacing them if necessary.

Soldering connectoins.

Spot welding (typically only if connection at cell has failed or cells need repalced. )

Knowledge of BMS, the possibly ways to reset them and what causes them to shutdown.

Advanced charging techniques and/or equipment.

Colorado: Hi-C https://www.hicbattery.com/

Michigan: https://netherswholesale.com/

Nevada, Las Vegas:

Ebike Market Place 6585 Arville St, Suite A
Las Vegas, NV 89118 Ebike Market Place  https://ebikemarketplace.com/products/polaris-e-bike-battery-replacement?variant=8035110027294 
or Rechargeable Power RPE https://rechargeablepowerenergy.com/

California: https://www.fthpower.com/ Fth Power 20801 Currier Road, City Of Industry, CA  91789