Step 1: Confirm it is in fact a bat.
Step 2: Freak Out.
Step 3: Open door more.
Step 4: One run for a camera the other grab the broom.
Step 5: Wait like a batter (broom stick) and catcher (camera) for emerging bat.
Step 6: When bat emerges fend off bat with broom stick, duck if you have the camera (take no picture due to fear) and run away.
Step 7: Get over rush of adrenaline.