Hey, new tl owner here.

So yesterday, I parked my tl and locked the doors using the key fob. After the second press, i realized that there was no beep indicating that the alarm was armed, but i didn't really pay attention thinking that i just didn't hear it.

This morning, my car's battery was drained. Any ideas where the problem might be? I'm pretty sure all doors/lights were closed/turned off.

 

The HFL (hands free link) is the first notorius culprit to battery draining. You can test it by selecting it on the MID to see if it's malfunctioning. If it is, it will simply say "Booting Up" indefinitely.

I'd start with that. Then move to the battery to see if maybe it's not holding a charge.

 

I had serious battery drain anytime I didn't drive my car for four or more days. I replaced my battery 3 times in 1.5 years. I finally took it in to the dealer. The Hands free link was found to be draining the battery. When I thought about it, my HFL stopped working over the same period of time as my battery problems. They disconnected it.

 

hfl is the problem, do a simple search and you will find your answers

 

The doors won't lock and therefore won't 'beep' unless they are all closed. That being said I believe the lights do eventually turn off if a door is left ajar, so HFL is most probably the culprit

 

did you check to see if your trunk was closed? that trunk light can drain it too. It would also explain it not beeping.