Restore a 40v Li battery that holds charge but won't recharge?

I have a 40v, 2 AH, Type 4 Black and Decker lithium battery for a trimmer that is capable of holding a charge but when placed in a charger produces a flashing error signal. I have another of the same battery that charges ok, so the problem isn’t the charger. Also, the flaky battery will run

Battery Fix - 40V won't Charge! Solved - Nailed it.

Why My Lithium Battery won't Charge?

How to Fix Dead Lithium-Ion Batteries That Won't Hold a Charge Anymore « Hacks, Mods & Circuitry :: Gadget Hacks

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The science behind lithium battery not charging and how to solve it-Tycorun Batteries

How to reset this 40V : r/ryobi

40V MAX* 4Ah Battery

Restore a 40v Li battery that holds charge but won't recharge?

BLACK+DECKER 40-V 2 Amp-Hour; Lithium-ion Battery in the Power Tool Batteries & Chargers department at

The science behind lithium battery not charging and how to solve it-Tycorun Batteries