In reply to GW7AAV:
If you’re not ham fisted they are easy to re-cell yourself. Wrap the pack in cloth and them hit along the seem with a small hammer. This is normally enough to crack the glue/weld and the pack can then be opened and the cells removed.
It’s likely if the cells are series charged than most will be OK and just one or two will need “education” so they “get with the program” ! This is best achieved by charging up a Schwarzenegger sized capacitor (say 70,000uF) to about 12V and then connecting the capacitor across each cell. There’s enough energy in the capacitor to melt any internal resistive paths in the cells. That can occur with poor charging regimes. But there’s not enough energy to do any damage. Don’t use a car battery or PSU, you need something that has a finite amount of zap as you can sometimes spot weld the wires to the cell. You don’t want to do that with a car battery (capable of >5000A in a short circuit).
Reassemble and cycle the pack a few times and you should find 85-90% of normal service has been resumed. However, if the pack doesn’t respond you can buy tagged cells and assemble them yourself. Or if you are a complete CBER (Cheque Book amatEuR) you can send the packs to Strikalite (http://www.strikalite.co.uk/) who will re-cell them for you. Or you can look on eBay and see what the Chinese cloners are selling on the world’s biggest tat bazaar just in case they have a suitable pack at a reasonable price.
I’d give them a zapping first as you have little to loose.