Help! New battery but wont start.
 

My 2008 HHR LT has been sitting for years with a dead battery. I replaced the battery but when I turn the key I can only hear the fuel pump engage. The car still will not start. I was told this is a security issue. Does anyone know if that is true or have had the same problem?

No, not security if you are using the correct key. Why has it been sitting?

I would check the wires for signs of varmints chewing on them and nesting in places like the air filter.

I have been overseas for a long time. I've checked everything and don't see any signs of wire damage but I guess it could be anywhere. The fuel pump engages but it won't turn over. I was told that this because of the battery being dead for so long.

One post is enough, you have to refresh the page sometimes twice.
First check for voltage on the big red wire on the starter, it should be always hot.
If it is not new starter.
If it is check voltage on the purple wire to the solenoid when your assistant tries start the engine.
if there is 12V new starter.

Ok thanks.

Let me amend that.

Always hot to the starter red wire goto next test
If no power check the connection at the big red wire on the fuse box.

I read - heard the buzz of the fuel pump.
But you do not write about the clicking of a starter. If the starter does not click when turning the key (does not try to touch the engine), then the electricity does not flow to the starter.
It should go from the castle to the starter. Check wires, connectors, fuses. Perhaps Bendix needs repair.

And really ... Why was the battery discharged? I think the answer to this question will be the key to solving the problem.

Because it sat for several years.

Welcome to the site, if it sat for so long, where did it sit?
A garage, possibly damp in the winter?
Corrosion at the ground points in the ignition switch , in the relays ?

Hope it's not a flood car.