Why won't my Jeep start and why is it through gauges?

Why won't my Jeep start and why is it through gauges? My Jeep won't even begin to turn over, behind the instrument panel there's a clicking and all of the gauges go haywire when I go to turn the key. Replaced the starter 5 months ago, battery is 2 years old and I just had it tested all good. I'm pretty mechanical and have checked the grounds for the engine and to the starter but can't for the life of me diagnose this... Any ideas??