Hi: I have a 2001 E53 X5 with 4.4i engine. My daughter complained the music stopped working and the head unit seemed fine, so I checked the amplifier in the rear quarter. I pulled out about 1 liter of water and the bottom of the amplifier was sitting in this water. I removed the amplifier and it's holding bracket. There seems like there is a device in the bottom of the quarter panel that is supposed to let water out. Does anyone one know if this is the case? If so, what is it called and/or what is the part number.

I'm afraid if I remove what I am seeing I will break it. It is circular like a blind grommet/plug, but there is a little button in the middle.

Thanks in advance.