DIAGNOSIS The plastic battery release latch on the drill is either broken or the spring behind it has dislodged.
FIX Inspect the black plastic latch on the drill's battery port. If it's cracked, you need a new battery port housing. If it's intact but loose, remove the battery and use a small flathead to gently pry the latch outward to see if the spring is missing or misaligned.
IF THAT DIDN'T WORK Sometimes the problem is on the battery side. Check the notch on the V20 battery pack for cracks or deformation. A damaged battery case can prevent a secure lock.
HEADS UP Don't tape the battery in place. A loose battery connection under load can cause arcing, heat damage, and is a safety hazard. Fix the latch properly.