So I started the XK tonight and the lights did not all go off as usual after ignition. The Brake and ABS warning lights stayed on. I shut it off and restarted. This time the same deal, except now with the check engine light joining the party. Also I notice the ASC button in the console was on, and I couldn't switch it off.

The manual says brake fluid could be low, but I checked and that isn't the case.

Any help would be greatly appreciated.

 

Systematic of a low battery, you said I started the xk tonight, so you don't run it every day? Just sitting there is battery draw ands pending age/condition of battery this is what you might see. Many Many posts on this.

 

+1 on the above. Give the battery a full overnight charge and then see what happens.