Jim in Akron

I have an 18v makita hammer drill xph03 that just today started doing that. On the newer batteries that had 4 bars , in 2 seconds it was down to 1 and flashing . Then i tried an older battery without a battery gauge and it worked for a couple seconds , I set it down and when I picked it back up battery was dead and it was hot as hell . So it’s obviously a short somewhere but where could it possibly be ? jim