2005 Dodge Neon Starting

Please provide some symptoms or details. No engine power? No electrical power? What works and what doesn't?

Nothing works

First measure the battery voltage. It should be 12.6 volts. If it's near 12.2 volts, it's discharged. If it's closer to 11 volts, it has a shorted cell and must be replaced.

Turn on the head lights so some current is trying to flow. That will make a bad connection show up. Follow the smaller positive battery wire to the under-hood fuse box. Measure the voltage on that stud, not on the terminal crimped to the end of that wire. If you find less there than at the battery, clean and tighten that connection.

Follow the smaller negative battery wire to the body and be sure that connection is tight and not rusty. Move your voltmeter's negative probe from the battery's post to a paint-free point on the body. You still should have the same voltage as you found at the battery.

If you haven't found the cause of the problem by this point, tell me what you have for voltage with the positive probe on that fuse box stud, and the negative probe on the body.