2004 V8 Vogue

Good evening. I had the cursed battery drain that removing fuse 49 resolves. I fitted a second hand sat nav unit in the boot in the hope it would solve it, it seems to have made it worst.. I've confirmed the sat nav red light goes out as does the light by the gearstick.
Has anyone got to the bottom of this fault..I have a fault on the xyz selector which I don't know if this is related..
Any advice would be great as it's really annoying

I had a battery drain when I got the car, turned out to be the blow off valve that sits on the battery, the nut that holds it in place was loose by a maybe half a turn, you wouldn’t think it would matter but it did, would go completely flat overnight.
The other battery issue I’ve had in the past was caused by the boot light staying on, only noticed when I’d removed the parcel shelf

youmitegetian said:

I had a battery drain when I got the car, turned out to be the blow off valve that sits on the battery, the nut that holds it in place was loose by a maybe half a turn, you wouldn’t think it would matter but it did, would go completely flat overnight.
The other battery issue I’ve had in the past was caused by the boot light staying on, only noticed when I’d removed the parcel shelf

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I would never I'd thought of that !! Interior bulb . Yes I checked that one. It' seems there are so so many differen problems

Yeah it’s a minefield for sure, the guy I got the car off had paid 2 days labour trying to find the drain, I spent a day at it, then purely by chance found it as I was pulling the multimeter away in defeat the car woke up so I knew I’d desturbed something, after that it was easy