Mercury Mariner Engine Not Cranking Over

Been Working On The Vehicle Listed Above That My Friend Recently Purchased. When She Got It, Someone Had Installed A Button That Ran A Wire...

When I Start My Car, It Makes A Clicking Noise Where The Gear Shift Is And Does It In Park, When I Put It In Drive And It Stops.

Has Been Sitting For 3 Years. New Battery. Will Turn Over If I Jumper The Start Relay, Dash Shows Drive, No Matter What Position The Shifter...