Ford Repair: no crank, battery cables, ground connector

Question
Hi I havve a 1995 lincoln continential and the starter went out so I replaced it with another starter and installed it and now I can't get it to crank. When I turn the key all the power shuts out as if the battery it dead/low, so I brought a battery and the same thing happened. The starters good I took it to a shop and tested it and the battery is good. I am thinking that it has some to do with a grounding problem or bad connections with the battery cables whether that be at the starter or battery post

Answer
Check all your connections, make sure they are clean and tight. With a 12 volt test light you can check for start power at the started, on the small wire conneciton, having someone turn the key to start for you. Also check the ground connector near the battery, has two wires about 12 gauge, sometimes this connector corrodes or comes loose.