After I attempted to install a sub in my 96 jeep grand Cherokee Laredo it will not turn over OR even crank. The gauges lights all work. The only other thing is that the stereo only plays FM thru the door speakers. but it plays cd and aux thru the sub..I replaced the starter an checked all the relays under the hood and fuses in both boxes. Somebody told me it could be a fusible link or mainline fuse. Could that be the problem? Where would I find those if so? I have rigged a push button start to the starter which works every time... But am looking to get a newer jeep so would like to fix this before I sell it.. Help!!!!!

Double check and make sure your battery cables are tightly connected. I have done this myself before. Installed the power wire to the battery and forgot to tighten the cable back down. Start with the easy and free things first...