So, tons of symptoms on this one, so I'll list them in the order they happened.

1. Both headlights went out within days of each other (assumed bulbs, haven't gotten around to replacing them, as I don't drive much at night, haven't actually checked the bulbs yet, will do so when i get home)
2. Key fob stopped working, chaulked it up to coincidence and assumed battery in fob is dead. (No idea how to safely open and replace the battery in that by the way)
3. Car will no longer turn over (starter motor doesn't turn at all), and on-screen display says "boot open" (figured out that's the trunk apparently), and "rear bulb failure". When turning the key the car appears to draw power (dash dims, radio briefly shuts off) but then nothing happens.

I have attempted to jumps start the car. No success. Checked all fuses, all are fine (even the ones under the back seats, I swear, silliest place for a fuse box). I am aware there are other tests to try out, such as checking the relays, unplugging the battery for a bit, etc. But I wanted to post this up here in case the community has any quick suggestions to try out, possibly (and hopefully) something super-simple I've been silly enough to overlook.

And in case it is of any consequence, there is a major dent in the car (due to an incident involving over-confidence in traction and hydroplaning) on the side below the gas cap, although at the time it appeared that the dent did not do anything beyond cosmetic damage (well, besides considerable damage to my pride).

But I am very open to suggestions, and in the meantime, shall pick away at the electrical diagrams and service manuals (MASSIVE thanks to cristo on that). As for my background, I am very comfortable with electrical work (if it turns out to be the body processor module as I fear, I am more then prepared to at least attempt to have at it with a soldering iron before replacing it) but not ENTIRELY comfortable with mechanical work (I will replace belts and cylinder heads, simple stuff like that, but the thought of opening an automatic transmission scares the **** out of me)

 

New battery, first thing.Just to be sure, don't bother trying to recharge the old one.

 

Wouldn't the failed attempt to jump the car rule out a dead battery?

 

You might be surprised.

Where are you connecting the neg cable when doing the jump?

 

Connected it to the trunk latch as indicated in the manual.

 

Well, that is good.

I've seen it more than once where a car will not respond to a jump but a new battery solved it all.

 

Jumper cables, often, can not supply enough current to start a car alone, the voltage drop across the long wires is just too high - they are instead used to partially charge the existing battery and to provide some additional current to that which the battery provides... this means that if your battery can not provide near enough current for starting, the cables can't make up for it alone. Often, leaving the cables attached for quite some time will provide enough charge to the battery that it can now provide the lion's share of the starting current - so leave cables on and alone for 10-20 minutes if you can't start with them immediately - often this will suffice.

But, fully charge and test the battery... if it tests poorly, replace it.

 

Ok. Update. Left the battery unhooked for 5 minutes, hooked it back up, and the car now starts up and runs, but the other problems remain.

The indicator says "boot open" and the button inside will not open the trunk, even though it is secured shut, the key is required to open it.

The indicator also says "rear bulb fail", which I discovered to be the rear fog lights. Not that I ever used them anyways as heavy fog conditions are fairly uncommon here.

Both of these issues happened simultaneously. And will be looked into more tomorrow (more fuse checking, more relay checking, etc. etc.) I shall continue to use this thread to detail my progress. I know the number of times I've seen on forums "oh nvm, figured it out myself" and been stuck wondering what they figured out, so I plan to leave a full documentary of this.

 

Open the trunk and pull the plastic cover off the right boot (trunk) hinge. There is a bundle of wires that pass through there. They frequently break, as in, they all do it eventually. Unwrap the wires and fix any existing broken wires securely. This is posted on every Jaguar forum in the universe. The headlights sound like a relay. Not uncommon. There are a bunch of identical relays that can be swapped to test.

 

dejavu, I think I read that same statement a few weeks ago

 

First off, thank you all for the super fast responses to everything, I'll admit, I was originally posting as a sort of "well, someone MIGHT respond, couldn't hurt".

I'll look into that wire cluster when I get off work, makes perfect sense for that to be the issue. Lot better then the worst case scenario I was thinking of. And as for simple things overlooked, I totally didn't think "oh just swap in a known good relay" and instead was trying to fiddle with a multimeter and signal generator.

 

Well, update. swaped the relays between the front fog lamps and the headlights, and voila, headlights work now. As for the trunk issues. I noticed a fuse was bust in the luggage compartment fuse box. Replaced it, and POOF my security module let out the magical blue smoke. So looks like I'm in the market for a new security module.