I have a 2000 jeep cherokee sport and it will not start with the key anymore, there is no clicking sound when you try to start it and battery is brand new, but i can jump it on the starter, my husband put in a button starter and that worked for 4 days now nothing works except putting my hand in the HOT engine and jumping it with a screwdriver please help cause i am going nuts

First question is have you checked and verified that all the grounds are good? (there are around five ground points on the block). generally several small ones as well as large one from the engine to firewall and the main one from the battery. some computers have a few that attach to the fender as well. To the best of my knowledge, the body control module has nothing to do with starting but can act strangely if there is a bad ground.
Next, is there power coming out of the ignition switch when you turn the key to the start position? Is the neutral safety switch good (usually on the right side of trans on most common automatics) Have you checked for power at the starter relay and at the small wire on the starter? Testing that eliminates a lot of searching for answers...If power is getting to the starter trigger and the starter main terminal then most likely the starter has failed. I wouldn't even begin to look for a bcm till you have tested and verified everything I have said. First question is have you checked and verified that all the grounds are good? (there are around five ground points on the block). generally several small ones as well as large one from the engine to firewall and the main one from the battery. some computers have a few that attach to the fender as well. To the best of my knowledge, the body control module has nothing to do with starting but can act strangely if there is a bad ground. Next, is there power coming out of the ignition switch when you turn the key to the start position? Is the neutral safety switch good (usually on the right side of trans on most common automatics) Have you checked for power at the starter relay and at the small wire on the starter? Testing that eliminates a lot of searching for answers...If power is getting to the starter trigger and the starter main terminal then most likely the starter has failed. I wouldn't even begin to look for a bcm till you have tested and verified everything I have said.

I'm totally lost...I never said anything about a fog light switch. Your starter circuit has little or nothing to do with the computer and even with the computer removed, the engine would still turn when the key is in the start position. Connections cannot be checked by looking at them or wiggling a wire. Continuity needs to be tested using a digital multi-meter, or by removing each connection and cleaning it off. For test purposes, you can pry off (carefully) the plastic cover on the relay so you can get to the legs with a meter probe. I've seen a few that had a good relay but there was no ground at the relay coil connection.In that case, the start signal gets to the relay but the relay does not energize, so nothing comes out to the starter trigger wire. Adding a separate ground (to the connector under the power distribution center) will work in that case. I recommend you find and buy a chilton manual for your vehicle. their wiring diagrams are decent for what you need to do there.
Have you tested the voltage in and out of the neutral safety switch? (on right side of trans) I'm totally lost...I never said anything about a fog light switch. Your starter circuit has little or nothing to do with the computer and even with the computer removed, the engine would still turn when the key is in the start position. Connections cannot be checked by looking at them or wiggling a wire. Continuity needs to be tested using a digital multi-meter, or by removing each connection and cleaning it off. For test purposes, you can pry off (carefully) the plastic cover on the relay so you can get to the legs with a meter probe. I've seen a few that had a good relay but there was no ground at the relay coil connection.In that case, the start signal gets to the relay but the relay does not energize, so nothing comes out to the starter trigger wire. Adding a separate ground (to the connector under the power distribution center) will work in that case. I recommend you find and buy a chilton manual for your vehicle. their wiring diagrams are decent for what you need to do there. Have you tested the voltage in and out of the neutral safety switch? (on right side of trans)