2003 xk8 no start

Just a click and no start. Battery is full.
Erratic behaviour of windows and will not come out of gear (sounds alarm)
Any suggestions?

Check the battery connections to make sure they are clean.

Did the charge battery thing and disconnect in hope of computer reset but no go yet.

If the red LED by the gear selector is on and you have a P1260 fault code the car may have got itself into theft mode. This happened on my 1997 car when the Security and Locking Module got out of sync with the Imobiliser part of the Body Processor. The car stopped recognising the key.

Thanks Eric
Good to know for later.
Light is not on.
I guess a scan is next.

Discovered a battery defect which prompted a few codes.
Replaced battery and most problems disappeared.
Still have check engine light on for lean code and high pressure on fuel rail.
Is it possible that fuel filter restriction could cause fuel problem?