I got in the car this morning and the diplay will not go past the Jag logo in my 2008 XKR.

Although the a/c will not diplay, the blower motor speed is adjustable and it appears to get warmer and colder with the corresponding buttons. I pressed the on-off button and home button but no response. Blutooth would not do anything.

Where do I start looking?

Drive it to dealership and have them check your battery....

The battery is always my first "go to" but the cranking speed seemed normal. No struggles to start at all. Everything else with the car is perfect.

Nearest dealer is 60 miles from the house and I needed to be at work on time today.

I will start diving in to the fuse panels tonight.

if you have a battery charger , charge the battery fully and see what happens, suspect it will fix problem, if it does, next time it happens go out and get an AGM batttery.

Crossing my fingers!

I went to lunch and everything was back to normal. I will update if it happens again.

The voltage can drop too low for some of the electronics (actually, usually during cranking) long before you sense any change in cranking speed.

Almost certainly battery-related, though it may be a one-off glitch. For future reference: in order to reboot some of the electronics modules, just switching the car off & restarting isn't enough, because it stays in 'convenience mode' with many of the modules still powered on. However, if you stop, get out and lock the car, most things power off. When you unlock, they reboot.