Hi.
The charge regulation voltage failed and applied about 5 Volts to several 16850 paralleled cells. All kaput. Did it create an irreversible chemical reaction with not a chance of recovery, right ?

 

Probably lucky you didn't have a fire.
Not sure it's worth thinking "can I fix these" as they might now be unreliable in some way and future fire risk could be a concern.
I've never had a fire with a battery but then I've never abused one, I do know there's always been a general suggestion that charging problems can cause problems.

 

If the Li-ion batteries are incorporated in a 'pack' their apparent failure may owe to an open thermal 'fuse' -- otherwise they're probably "beyond the vale" --- I concur with Post #2 as regards safety/reliability concerns attendant to 'resurrected' cells...

Best regards
HP

PS -- Why on earth do you wish to abolish the decibel???

 

That depends if the cells have internal protection circuitry or not. But either way they are probably toast.