GTi 6 Won’t Start

[C2K]

Stuff like this is generally an earth, or permanent short to earth. I've seen things cause one light, no lights, no cranking but haven't seen much that would explain your symptoms.

Start methodically. Test, don't look at, all the fuses. Check the fan loom and bay earths, primarily the Gearbox one. I remember getting lots of lights then couldn't start the hdi, but that wouldn't even crank with broken main earth. You're getting some sort of short circuit or back feed, so the issue is electrical, but needs to be something major to prevent starting. I'd suspect a dicky barrel or loom if you weren't getting it to crank on p3 ignition. 

That fan loom can cause fires, as Niall says. Regardless of whether it's causing your issues it's well worth a visit. Keep. An open mind, you could potentially have two problems, one causing the lights and another causing non start.

Cully is your man for electrical questions and you've got his attention.