2006 LS. Car has started and ran fine since last battery was installed 5 years ago. I'll try to make this as succinct as possible:

• It recently sat for about 2 weeks, and when I went to get in the car, the car would not respond to the FOB.
• New FOB battery, no change.
• There was a USB charger left plugged into the car, which probably killed the aging battery.
• The only key cylinder on the car (as we all know) does not work at all.
• No amount of graphite or WD40 helped unstick the lock.
• After 3 more weeks of sitting dead, I tried to hook a battery charge up from the underside of the car. This did not allow me to enter the car either.
• Removed the air dam from the car so I could unlatch the hood from underneath, which I was able to do.
• Battery was < 2 volts. Hooked a jump pack up to the car, voltage measuring good from jump pack.
• Voltage also reading correct from cars battery terminals.
• Figured with just the juice from the other battery/charger, the car would open, but it still will not respond to the FOB.
• Disconnected battery entirely for 10 minutes. Reconnected. Still does not respond to FOB.
• Holding various buttons as recommended by google does not work.

Does the car forget it's programming for the FOB if it is dead for too long? (Could not find a google answer to this, which was very annoying) What can I try next? I would love to just get in the car and try to start it to see if it still recognizes the transponder in the key. Do I have to start it before the FOB will work again? The car is quite rusty in upstate NY, I do not want to put any money in it just to get it open and started if I don't have to. I find it hard to believe the FOB went bad at the same time the car battery died. Too much of a coincidence. I don't have a signal tester for the FOB RF.

Any help is appreciated.

 

A factory service manual may have the answer to this ? All the programing in these cars goes thru the Radios. If the battery is that dead the car may not start just because there is no constant power.
You might want to borrow a battery from another vehicle and put it in there and see what happens.
The next thing to try is check with the Chevy Garage and see if they have any ideas.
The car does have a manual lock and if you can get a rod into the upper part of the window and find that lock you might be able to open it that way. Good Luck!

 

x2. With everything that you've gone through, I would have 100% just called a locksmith/AAA by now to just get into your car real quick.