If the batteries plates are sulfated off it will still take a charge but will have a drastically reduced capacity, It'll go dead fast. Have it tested and they'll put it on a carbon pile that will tell you how good or not the inards are. It got hot because it was being overcharged, for whatever reason, alternator, voltage regulator or just bad grounds. The charging system must be checked out from one end to the other or next time the battery could melt down and you'll have acid everywhere.
