My 2004 XJ8 sat for about 6-7 months and the battery died. Recharged and tried to start... makes an unfamiliar, weird clicking noise. I wondered if there is a reset process to restart..?

 

Sounds like relays due to not a strong enough battery. It may well need replacing (or if "new" charging with at least 10A for 12+hrs)

 

+1

Sitting for that length of time without being on a battery tender is likely to have irreversibly affected the battery.

The vehicle is also likely to have lost settings stored in volatile meory such as window travel limits and radio pre-sets.

Graham