Einhell TE-CD 12 Li Battery Repair: Reviving Damaged Batteries Due to Cold Storage

Hello, as in the topic, 2 almost new einhell batteries have died, only charged a few cycles, unfortunately they were left in a cold garage and the charger shows them as damaged, the question is, can they somehow be saved?
Einhell te-cd 12 li

I'm afraid that only the replacement of the cells can help.

Probably the batteries were discharged below the acceptable standards, so check the condition of the batteries with the meter. If they have too low voltage, the electronic charger will have a charging problem. In such cases, I charge the batteries with a traditional charger beforehand, and after the batteries have obtained a voltage close to the nominal one, I connect them to the appropriate charger.
Whether the charger is functional, maybe the batteries died as a result of overcharging.

The batteries are probably not so discharged. But should you upgrade them to a higher value?

I have the impression that one of the cells in the battery is damaged. Try to check each one separately with a meter and replace the suspicious link (without voltage) with a working one.

Sometimes the reason is electrical engineering
You have to check - charge individual cells to 3.5 V
in such a condition, the charger must charge them, if not, the electronics are damaged