2004 Taurus won't start, only clicking noise when I turn the key.

Could be Head Gasket blown , has no effect on oil level but will give you the warnings that have come up

If the engine cranks over and does not run, you need to decide if it is a fuel problem or an electrical problem.
If when you turn the key you hear a click, you probably have an open in the starter.

that item is called a relay switch. it toggles on and off depending on which electrical component it is connecting. if it's blown, they are cheap and easy to replace like a fuse, but you'll need to look at the fuse box chart (usually on the underside of the lid) to determine which one and where it's located. You can't look inside the relay to determine if blown, but you can replace them one at a time to test...
Also, if you're experienced in electrical, a paper clip can be used when the relay is out, to connect the circuit that you need. use tools and or gloves when attempting this method.

could be the starter relay .

You have a defective battery.

It's your starter. Find location of your starter. By the flywheel. Then. Bang on it . Your car will start. You still need to replace the starter.

sound like dead battery ask someone for a jump start
if this fails may need new starter

Need to take it back to the dealer so that they can program both keys correct. there should not be any more charges for this being they did not do it right the first time.

needs a starter- or cable- if you had to tap on it for it to work its junk-

Depends on the sound that it makes when you turn the key over.

Clicking noise...usually the starter

If it sounds like its going to start, but doesnt, most likely the battery.

If you have replaced the battery recently, then its the alternator.

Sometimes there can be oil build up over the spark plugs so it doesnt get the spark to start.

Hope you get it fixed!!