Charles
Welcome to the club/forum.
As for electrical/battery problems, these are Jaguars and you will soon grasp that they are charge hungry. Parasitic drain is very common and you will need to keep your battery in good condition and well charged. The popular piece of equipment is a CTEK MS 7 0r MS 10, Charger/Re-conditioner. I put my S-Type on a CTEK MS 7 as often as I can and certainly at least once per month. It really does stop a lot of unnecessary yellow light and messages that are only generated because of low battery charge. Well worth the investment and effort to keep battery in good condition and charge.
Best Wishes and Regards, John