I just purchased a 2005 Acura TL and if the car sits for 2 days the battery is completely dead. Fob will not even open the door. The dealer put in a new battery and it still did it. What is the problem?

Battery cables ? Hard to say for sure Cassandra ,Would need to do so electrical testing ! Do you own a DVOM - digital volt ohm meter ? There are videos on youtube showing how to do basic automotive electrical testing ! First one I would do is voltage drop testing the starting circuit , charging system ! Voltage Drop Test

Check the battery cables again. Both positive and negative. Check the other ends of them also. Could be a loose connection or bad contact.

Open trunk access in rear seat, use something to grab and pull emergency trunk release attached to latch.

Raise the car up,support it in the front

Put a battery charger on the battery cable
at the starter and the ground to the sub frame

Charge the battery for a couple hours,then try to
open the door with key fob

u shud scan vehicle 1st--a flaw in the wiring harness may be present or solenoids etc cud be staying on--go in engine area and chec the maxifuses that connect to alternator-if burnt then batt wouldnt charge--secure a repair manual

Do you have a keyless entry FOB. If you do replace the battery then program the system. Unlock the doors turn the ignition key to the "ON" position then press either the lock or unlock button of the FOB turn the ignition key off.Now turn the ignition key on again and press either button on the FOB. Turn the ignition off again. Do this 3 times. This initiates programming for the power door locks. Press the lock button of each remote one at a time to be stored in memory. this must be done within 10 seconds of each remote.
3 remotes max. Turn the ignition off and remove the key to complete programming procedure. then test each remote.

You either have bad terminal connections on your battery or the anti-theft system has a system or sencor problem . I would really recomend that honda/acura check your electrical system and anti-theft system

I had this too, on the left rear door handle cover. If you were careful, had a small and thin screwdriver (e.g. the kind you'd use on eyeglass hinges), you could bend back the tabs that hold the cover on and snap it into place. My mechanic told me the same thing, but told me if I were patient, the cover might snap on...saving me about 2 hours' labor cost. It worked!

Check battery for dead cell.

Your navigation code and radio codes writed on stikers on glovebox. Just open your glovebox and look on left side of gloivebox, not inside but outside. Open glovebox and look on left side. On my 2005 Acura RL NAV and Radio codes is different but it both on glove box. Sometime you even need to remove your glovebox cover to see those codes.