Bad starter?
Bad neutral switch?
ignition switch?
If you are 100% sure nothing is on pulling power from the battery and it will not hold a charge then the battery has a dead cell and must be replaced.
it could be your starter selinoide which should be in the engine compartment near the battery and the big waire from your battery goes to it!
nothing works and I replaced the battery. to the fob
Nothing, as long as they're both the same voltage. The 18 Ah battery has just slightly more power. It will work perfectly.
If the post has actually come out or is loose and wiggles there is generally nothing possible that can be done to repair it, the entire battery will need to be replaced.
make sure the small wire is hook to the post
Double check the battery cables at the battery and at the engine, be sure they are clean and tight.
2004 Chevrolet Tahoe?
Sounds like the ignition switch.
Make sure the battery cables are making good contact with the battery and are clean and tight.
Make sure that you connected the battery cables properly. The red cable goes to the positive side(+) the negative or black cable to the (-) side.
Check the fuses