What the little hole in the bottom of the back cover for?

[Tom Mort]

I just bought a used droid incredible. It came with a case. I notice that there is a hole in the case on the left side as you look from the bottom while the phone is face up. There is also a hole in the lower back cover here too and you can see the red of the inside.

I sometimes have the phone lockup and have to remove the battery and reinstall it to get it to work again. This is inconvenient and I imagine would wear out the locking latches. Is the hole access to some sort of pushbutton switch to disconnect the battery temporarily? I have tried pressing it, but, I didn't notice anything happen.

Can anyone tell me what this is?

Thanks in advance