2001 s80 Need Help - starting issue

[jrathbone]

So we just got this 2001 S80 2.9 and when I went to start it, I had trouble turning the key in the ignition at first. It eventually turned. I just figured, new to me car, just getting used to it. Well it happened twice after that, that same night and then the third time, I really didn't think it would turn. It finally did, but now the car wouldn't start. The interior lights came on, the radio was on, the dash lights all it up flashing and it made a constant clicking sound but wouldn't start. We jumped it to see if it would work and sure enough, it started right up. Checked the battery charge. Volts read 12.7 off and 14.2 running. We thinking the battery is fine. We did a trial and it seems just by leaving my door open for 10 minutes or so, like I had before it wouldn't start is all it takes to draw enough power somehow to stop it from starting.
Possibly related or unrelated is the sunroof. It does not work. the previous owner said it was open and then wouldn't close. Luckily one day it happened to work and he closed it and left it closed. My husband heard from someone that there is a sensor for theft or something that can stop the sunroof from working then the doors and trunk, which seem to be working although we were told had stopped working with the auto locks, and then eventually the car won't start if this sensor goes bad. Has anyone heard of this type of problem?

Wondering if this could all be related or if I am looking at multiple problems.

Thanks for any help you can offer!

[draser]

If your alarm circuit is anything similar to S60's they say the sunroof circuit is common to siren's. If that is correct, can be verified with schematics, then I'd check the siren condition, since it has a battery in it that leaks and destroys the control board affecting sunroof and all car comm bus. I'd try disconnecting the siren module, then see if sunroof works and car starts.