The cells are ruined.
Dont try to recharge them,If you do, you will have a time bomb on your hands.
They may take a charge and even function normaly for a short time, but they will eventually ignite, and when they do I just hope that you are out flying and not sleeping with the airplane somewhere in your house!

Its not a joke , more garages, houses and cars have burned up from mistreaded lithiums than I can count.

I have used them for years now, and I always store them in a sealed metal amo box in the garage.
I never keep them in my planes when I am not flying.

Originally Posted by arrow

(b) Is it common for a charger that is not powered to drain the batteries?

Yeah regrettably it's a fairly common problem I hear. Normally it's only a few mA, but your battery's only 170mAH? A few mA would indeed drain that in a couple of days. Of course there are also chargers designed not to do this sort of thing at all too.