There are a couple different ways to restore nicad batteries , first the one I know works has fixed 4 or 5 18 volt dewalt batteries.....

If you have a mig welder you can turn power all the way down turn wire speed down and zap the battery 4 or 5 times then put it on the charger.....

Or you can insert battery into the charger then plug/unplug the charger several times until the trouble lights go out and the charge light comes on

There are video's on these and more ways to repair old nicad batteries.... Like I said I have done the welder trick with success I would imagine if you have a 36 volt charger it would probably do the same thing as the welder.