SAME PROBLEM, replaced battery in both fobs....

Have you took your fob in to be tested. They can test it at automotive places , usually free. It will tell if it has power or not then possibly replace the battery. Or may need a new fob all together. Might have to order one from a Toyota dealer.

No mention of make/model but does key fob open doors OK? If so it isn't the fob batteries... Could still be a bad button on the fob but it could be a balky solenoid on the trunk latch. Maybe try 12V direct to the solenoid?

First if you have another remote (FOB) try it. If it works problem solved.Replace the battery. Replaced the battery in both fobs. The only other thing it could be is the reciever in the car. Dealer time.

There are some testers for the FOB on the parts counter of most major autoparts stores. This way you can find out if its the FOB or the car. Some cars have an Electronic menu which controls the Alarm chirps and response to the FOB. What can happen is a Oil change Tech can erase the wrong setting for the oil change interval and disrupt the settings for other things.

First things first...replace the cheaper part first, the battery. It that works, great! If not, then you may need a new key fob then have it programed to your system.

Do not panic but instead consider calling a dealer to avoid making any mistakes here.

I work for a doctor and a patient just had this same problem. She had a extra fob in her trunk so we opened the trunk with the key and got her other fob but I am wondering why the key does not fit the lock on the driverside

Assuming the car battery is ok (if not, buy a male to male cigarette lighter at the auto store and connect to another car until charged enough to unlock the doors...but don't try to crank the ignition!). The trunks won't open if the battery went dead with the alarm set because arming the alarm physically locks the releases.

Sounds like the key code is switched off because you replaced the key fob battery. Try unlocking the car manual with the key in the door lock. Then switch the ignition on to reactive the keyless entry. If this does not work, you might also try pressing the fob unlock button with the key in the door lock until the dash led flashes.

Yes, insure that you have power to the trunk lock inside trunk, If not could be lose/broken wire or shot fuse. I am sure the key fob does work for the doors? If not have key fob battery replaced. Also, a quick check on power to trunk lock, check to see if have remote power button inside car, if it works power is good. Defective key fob would then be indicated.