see your Chevy parts man.
One reason that your keyless entry may not work is that the battery is dead, take it an auto parts store and have the keyless entry battery replaced. If that does not fix it you will need to take it to the dealer to have the keyless entry reprogrammed.
how do you change the battery in a 2002 jetta keyless entry pad?
How program my keyless entry remotes for 2003 chevy malibu
CR2032
My daughter called tonight with this question-her Dad called a mechanic friend-he checked around for an answer--this is the battery in your remote keyless entry--the thing on your keyring.
CR1620
Keyless entry was an option for the 2005 Chevrolet trailblazer model year. Most 2005 Chevrolet trailblazers came with the keyless option.
To install a keyless entry system in a 2009 Chevy Cobalt, start by purchasing a compatible keyless entry kit. Remove the driver's side door panel to access the wiring harness. Connect the keyless entry module to the vehicle's wiring according to the installation instructions provided with the kit. Finally, reassemble the door panel and test the keyless entry system to ensure it functions correctly.
Open the keyless remote and you will see the battery take it out and replace it with the same size.
Not with the keyless entry pad or remotes - unlock your drivers door using your key That's what I had to do on my 1995 Ford Explorer when the battery had a dead cell and there was no power
Rayovac BR2335
its a CR 2032