NO! First off, drilling a hole in plastic case holding batteries would be dangerous. Secondly, there is no air pressure to relieve. Third, case swelling is caused by the batteries inside themselves swelling. Fourth, hole into actual batteries would not do any good.
To remove the battery from a drill, first remove the battery and open the side of the drill. Then, apply conformal coating to the inside of the drill. This coating protects sensitive electronics from harsh elements. You can use a silicone or lacquer-based coating for this. Apply 2-3 coats for safety. If possible, open the battery and apply the same coating to it.
A drill battery should be used properly. Use the appropriate tool mechanisms for the material each time. Do not leave the tool with the battery attached for more than 12 hours if it is not in use. Avoid storing the battery in high humidity areas or leaving it out in the sunlight.
Drill batteries can be recharged using a specific charger. The batteries are made with small size Li-Ion battery cells connected by serial/parallel to have the suitable voltage and capacity. When the drill battery is connected to the tool using the special socket, it is charged.
To protect a drill battery, first remove the battery and open the side of the drill. Then, apply 2-3 coats of conformal coating to the inside of the drill. You can use either silicone or lacquer based coating for this process.
Pour in the lead and let it sit. When hard, drill a hole in, then tap out the hole. Should be good as new. Don't breath in any fumes from the lead. May be a simple fix that would work; I like the self tapping bolt myself. My friend owned a battery shop, and they would burn new terminals on batteries all the time.