I recently bought a 2000 S80. When I bought it the sunroof didn't open nor did the overhead lights work. The battery has been dead since I purchased it but now it is charged. I cannot open the sunroof and the overhead lights do not work. What is in common with both? By doing a Google search I read a few posts about removing the alarm fuse, didn't work. I also read something about locking and unlocking the doors with the key 3 times, still didn't work. Any suggestions? What's the common denominator between them?

 

Hard to say.
Could be a UEM. Upper Electronic Module. If I am not mistaken,the UEM controls the sunroof.

 

 

Its the circuit board in the rear view mirror. I recently had a similar problem. Basically you might have to replace the whole mirror being the module is in there. It wont be expensive but getting it programmed to your specific vehicle could be.

 

Contact https://xemodex.com/us/contact-xemodex/ (online form)

They will send you a diagnostic you can do with an ohm meter which will tell you if you have a hardware or software problem. If it is a hardware issue you will have to replace the upper electronic module (UEM) and they will clone the software to the replacement. The UEM is inside rear view mirror so your best option is to get one from an auto junk yard and send it along with your malfunctioning mirror unit to them for the cloning process. They will send it back to you for installation in your car. They charge $250 so your total cost will be $250 plus whatever you pay for the used mirror unit containing the UEM. You may be able to get someone locally to do the cloning but that isn't likely and they could really mess it up.