Ba 6Cyl Wont Start Batt1 Fuse Related Please Help

[Duz360]

Hi guys having a really weird problem and hoping someone here can help

my car wont start parked it in the garage Wednesday night under its own power but this morning nothing just clicks like flat battery

Here what I've tried

Done some tracking pulling fuses and such sound ive rounded it down to pulling an underbonnet fuse marked batt1

If you put that fuse in the battery voltage drops to 2.7v with it out 12.8v

put an ammeter inline draw is around 1amp which in my opinion wouldnt be enough to drop the battery 10v im thinking 10v drop is a dead short?

Any ideas or someone suggest something to try I have tried pulling every fuse in the cabin fuse box and the underbonnet fuse box and the voltage never goes back up

thanks in advance

[arronm]

Dead battery

[Duz360]

sorry should have said I took the battery 760cca out and had it load tested today and it come up fine so not battery unfortunately