get a tube of grafite auto parts store and cut the tip and spray it directly into keyhole then work key in and out.
Key should work like new.
Do not use wet lubricants on key slots
you have a problem with theft system possible key cylinder
The built in security system thinks someone is trying to steal the car. Remove key, walk away and try again in about 30 minutes with the right key, it should reset itself.
you got the wrong key.
put door key in passenger door turn it to the left and hold it this should de-activate the theft system
Won't the valet key open the trunk
willnot open trunk or locked compartments
cant its the computer
Press the trunk button on the dash board or the remote key fob
To disarm the factor alarm on a Cadillac Sedan Deville, place the key in the ignition and turn it slightly without starting the car. Leave it in that position for 10 minutes and turn the car on.
Counterclockwise beyond the "Lock" position
Use your door key.
start by checkn the Battery,I would put my lights on to see if they are workn, if they are not then it is your battery. If not could be your alternator.