GF's Hyundia Tucson will not start, battery is fine, help please

Hey all,
Wanted to post this over here instead of off-topic just because I think you might all have a better idea, and I would very much appreciate the help.
Quick story is my girlfriend was babysitting this morning and when she got back in her car to come home, it wouldn't start. It is a 2005 Hyundai Tucson. The battery was fine, all lights came on and everything, but when I tried to start it I would not even turn over. I didn't have time to fiddle with it because I had class and have several tests until Wednesday so we just jumped in my truck and went back home.
When I locked her car though using the remote, it locked just fine, but then after a few seconds the hazards came on for about a minute and then shut off. I then tried to turn the car on again for shits and giggles and of course nothing happened except some dinging and lights coming on (all the normal ones but the check engine and service light was on). Fearing that the lights would not stop flashing, I disconnected the battery but by that point we had to leave to get to class. It's now sitting at the house that she babysits for across town.
Any idea what it could be? Computer thing?
She is pretty good about coming to me when she thinks something's wrong with the car or its making a weird noise, so I doubt it had any problems starting or running on her way over there.
Any help would be great so we can avoid it getting towed and paying someone! Poor college kids struggling to pay bills in the first place.

Thanks for your help TW!

 

Could still be the battery. Sometimes the battery fails entirely, like you are expecting, other times it just deteriorates such that high amp loads cannot be satisfied. IOW, the battery may have juice to run the lights and other things, but not enough amps to turn the starter.

I would pull the battery and have it load tesed somewhere, or replace it with a working battery if you can make one available to test with, or try to jump start it.

 

Could be the starter or alternator has a loose connection too. Could be the key switch, a fuse, a short somewhere lol... just start with the simple stuff and work from there.

 

Check the code on the battery, you should be able to do that without pulling it. If it's 5 years old just replace it. I have had them go to the point that they would do what you are describing.

After that I like Stroked's idea about the battery cables..I had that gremlin once in my old Camaro, even swapped out the starter before finding that.

 

Battery is good (or at least should be) because it is only like 9 months old. And I did try to jump it...
Ended up disconnecting the battery, then reconnecting it, and now its working just fine.
Possible just a random computer thing?
I'm just glad it works again.. just hope it doesnt strand her somewhere again

 

Maybe a relay sticking. Or still could be starter issue

 

Make sure it's in Park.

 

Very possible, just chalk it up and see if it acts up again.

It could be as chriss said not all the way in park, that happened to one of my old cars but it wouldn't even click.

 

could be a starter going out, or a loose or corroded connection on the main power/ground cables.

also, does this have an aftermarket alarm by chance?

 

If you disconnected it and reconnected it, and all is working fine, then I would bet $$$ that there was a poor connection at the terminal that you removed, and by reinstalling it and tightening it back up, it then had good contact.

 

So we went and got the car from the house it was sitting at. It now appears that if we use the key fob to unlock it remotely, the hazards start to flash and it will not turn over. However, it we lock it back up using the remote, then unlock by putting the key in the door, then it starts up and runs just fine. There is a stupid aftermarket alarm on from the first owner.. and before this event, if you unlocked the car without using the remote, the alarm would just go off. You could not get in the car without the remote at all...
So this makes me think its something with the aftermarket alarm... what, I don't know.
Any ideas? I've never messed with alarms, but I have all the aftermarket stuff on my truck.
It's just weird that that morning, it was normal, she parked it, and then came back out and it totally failed on her.

I appreciate all your inputs guys!

 

I would be removing it! Any wires that looked like they have been spliced in, anything that doesn't look like it comes from the factory.

 

it may be a mercury switch or other switch from the aftermarket system.