Car won't start even when I jump it
 

I can't start my maxima, when I try my check engine light flickers and it sounds like a relay is clicking under the hood. My gauges also go all the way up then all the way down. Same when I tried to jump it. Any help?

Was the check engine light on the last time the car was working?
Have you connected a scan tool to see if there are codes?
How old is the battery?

So you just get one click and thats it? Double check the battery cables are tight then if its automatic, try putting it in neutral with your foot on the brake on a flat surface and starting it in neutral. If it still wont start, put it in park and have someone safely tap the body of the starter (not the solenoid of the starter, the body of it) with a metal wrench or metal ratchet while you turn the key. If it starts with the starter being tapped, the starter is on it's way out and you're best to drive it after that start to wherever you want to get the starter replaced.

Kind of sounds like the starter is pooched but the flickering CEL is weird, tapping the starter is free and the place i'd start

As chrome91 mentioned, one click is usually indicative of a bad starter. Gently tap the starter a few times with a long pipe and see if your Max starts right up.

This happened to me when the gas gauge was wrong and I was out of gas and didn't know it.

Check to see if you're getting power to the starter solenoid when trying to start! You should have 11-14 volts! If you do then see if you can rotate the engine at the crank pulley with a breaker bar and socket. Maybe your engine is seized or hydraulically locked. If it is rotatable then it's your starter! try taping the starter with a hammer, pipe or something heavy!