What's really up with my Chevy Malibu Lt ?

Having an issue on the 2012 malibu lt. The night before i was
listening to music for a bit in the parking lot of my house and it
stopped working and the charging port wouldnt charge my
phone..i kept trying to turn the key and it wouldnt start. So i
assumed it was a battery problem and waited the next day. Then i
tried the following day and then the lights turned on but it  was on
anti theft lock as well and I read to turn the key to a certain point
till the anti theft logo stop flickering and to turn it off and then
turn it on. So I did so and thought it would be that instead of the
battery since the lights turn on and cranked a little. But once I did
that the car completely turned off and has no light  whatsoever
and didn't crank anymore as if it completely died. Has any one
experienced this or is it just the battery ? Thank you.