Flashing blue light next to audio connectors

I've had my Dell XPS M1330 for a couple of years now, taking it just about everywhere I go, so it's suffered a bit of abuse. A couple of weeks ago, a part fell off the front of the laptop. The part was a small black strip of plastic that covered the audio/microphone connectors. I've outlined this part in a red box on the image below:

Now, behind this strip (which I have subsequently lost), on the right side, between these jacks and the SD/MMC - MS/Pro memory card slot, there are three blue lights (approximate location indicated by blue arrow). Usually the left one is on, the middle one is flashing, and the right one is off. At the moment, the right light is also on. I've also seen one of the lights turn red instead of blue when my battery was low, leading me to believe that at least one of the lights is some type of battery indicator. These lights were hardly noticeable with the cover over them, but now they are exceptionally bright. While watching a movie on my laptop, I have to put something in front of these lights, or I'm barely able to see the screen due to the brightness of these lights. I also do the same thing when going to sleep, because otherwise the room is kept rather well-lit by these blue flashes. I'm wondering what these lights mean, but more importantly, how I can turn them off. Thanks for any help!