Okay, I am a DIY type of person, and I am mechanically oriented. I have done complex engine repairs before, but I have no idea where to start on this electrical problem.

I have tons of electrical diagrams for the X300 which is what we are discussing here, and I might have to teach myself to read them, but I thought I would start in the Forum because I am really cowed by electrical system in this car.

1) The battery drains almost completely overnight.
2) I have a stored code for the EGR valve- P1401 ( I have a new valve in the Amazon cart)
note: this added just for full disclosure as it cannot be related
3) These power components do not work: Mirrors (both), Front Seat position adjustments (Both Seats), Driver's Power Window, Drivers Trunk release, right bumper fog light, LHR window switch, rear trunk button.
note: this may not be exhaustive, but it is what I have noticed.
4) If I jump the car it runs great and the battery charges well, I can start the car with no problems on a day I am driving it around, but by next morning it will likely be to low to turn over the engine.
5) The headlights had been replaced with brighter halogens (Again just full disclosure, but surely not related)
6) The power steering doesn't work properly at an idle so we maneuver in parking lots with one foot on the brake and one revving the gas a little to get power steering. (Just full disclosure)
7) I have tried disconnecting the positive and negative power cables from the battery and holding them together for a while (Reset?), but that changed nothing.

The car sat for about 1.5 years, and was given to us as a starter car or value towards one.

Everything accept the battery drain is tolerable, but I would rather fix it all, and I doubt I can afford a Jag specialist looking at it.

Can anybody give me a starting point, an approach, or a process to follow to find the root of the electrical problems? Does this should like it is all attached to one branch of the electrical system somehow? Again, I have all the electrical diagrams.

I am in the Riverside California area, and would be happy to be referred to somebody who would be willing to help for cheap or free. We are also interested in selling it potentially (we are working through that decision... Insurance costs, etc..

On a side note there is a disconnected small white wire with a female crimp connector next to the battery (seems out of place), and there is an open 1/4 inch black rubber tube laying next to the battery that heads out of the trunk through a grommet, but is connected to nothing in the trunk. No idea what these are for, and I cannot find any obvious place to connect them.