My 2011 Hyundai Elantra brake lights remain on. ( The only antecedent I can think of is i changed the passenger side brake light 2 weeks ago also I brought to the dealer for airbag recall last week)
That will drain your battery fast.
The brake light switch may have failed or possibly can be adjusted.
If the lights go out by disconnecting the connection to the brake switch then it appears the switch is shorted, or not adjusted correctly.
I had that happen to my Corolla just a few weeks ago. As posted above, good chance the problem is w/the brake light switch. In my case however the problem was a rubber spacer that fit on the bracket where the brake light switch pressed had fallen off. So look carefully on the floor under the brake pedal, see anything that looks like a part that fell off? I had to vacuum everything off of the floor, then look at the contents of the vacuum cleaner to find it.