Why is there a white light On my droid maxx 2

[AC Question]

Two days ago I kept my Droid Maxx 2 on overnight charge and when I woke up. I found the phone unplugged that my dad might have done but the phone had a complete black screen and a white light on the top. I somehow managed to get the phone back in it's position and after a few hours the white light went away. But since yesterday there is the white light again back on the top and somehow the phone is working perfectly fine I even turned the phone off and didn't use it but still it's been a day and a half since I have this white light I'm really paranoid olds help me to get rid of it I did everything even reset my phone but no luck and surprisingly the phone works completely​ fine.