Have a 2001 XK8 with 125.000 miles. Replaced dead battery now will not start. The things I have checked. Fuel pump comes on, motor turns over, all dash lights work, all key fob systems work comp 125 psi per each cylinder,stereo and cd work top goes up and down all electrical components in car work. Motor does turn over, Anti theft system will not turn off with fob if I trigger it to go off must disconnect battery. Yhis happened before and i found a thread that told me how to insert key in door turn back and fourth so many times insert into ignition and walla it starts. I did this only once and car started immediately with no hesitation. Am unable to find thread. has new cam and crank sensors fuel shut off valve has been checked. 41 psi at fuel rail fuel pump does come on. Did disconnect battery be fore and it worked not any more and touched cables together did not work but it has before not now

 

https://www.jaguarforums.com/forum/xk8-xkr-x100-17/

Wrong thread post in the above thread.