2000 Mitsubishi Eclipse GT won't start, replaced battery 7-10 days prior. was working fine all day, stopped for 20 minutes then nothing a single clicking sound. power seems fine lights, radio, horn etc... Would like to exhaust all options, first thought was alternator. I'm no mechanic, all I know is if you turn the key and it doesn't start...it's broke!!

SOURCE: Ignition key turns on but car will not start

I suspect the ignition switch is malfunctioning.

SOURCE: Cannot start 2000 Dodge Grand Caravan

No preferences as to charger, as long as it has trickle charge option (slower, but better for battery). Would like to see battery load test done by parts store to see battery condition, but a simple charge may be it. Let me know how it goes, hopefully you will have it up and running soon.

SOURCE: 2001 Saturn SC2 Electrical issue

I had the same problem in a 1997 SC2.  Turns out that finicky/broken door lock/unlock switches were causing an intermittent short.
I removed the 20A fuses to these locks in the switch panel under the radio.  Problem fixed.

SOURCE: 2000 Mitsubishi Eclipse GT horn not working

check the wires to the clip on the horn they rust and then there no connection

SOURCE: Grand Cherokee wont start, clicking coming from interior fuse box

Bare or burned wire, most likely battery cable or alternator cable near exhaust system which might be making contact with a metal part somewhere, off and on, because of bumps, vibration, etc.