The battery is fine. It was the charger that was faulty with a broken wire and loose component.
I have repaired the fault and the battery charges correctly now.
Hi, I am a bit late to the party but this might help anyone with this problem.
I bought a cheap Hilti drill with a dead charger. Opening the charger and carefully checking the board I could not find any fault.
Almost ready to give up I looked again and found one of the leads for L3 was...