Ok sorry chaps, long story but just want o give you the full picture.........

Was driving on the motorway, car spluttered, engine system fault (red) restricted performance, within 10 secs car died. Had had some previous issues with irregular fuel gauge readings where it did the same on 40km range on the tank, this time 250ish km's. Threw some diesel in tried to cranked a few times, didn't start, eventually battery drained and got low battery warning on display. Flat bedded to my shop and stood for 2 days. I also noticed slight dripping of diesel under then tank. Removed the battery (Varta AGM 1yr old) put on a 48 hour charge, then tested @ 12.8V / 950 SAE, installed the battery - and now MULTIPLE WARNINGS!!!! DSC not available, gearbox fault, check pedestrian system, steering column locked, park brake fault, engine temp indication fault, emergency brake assist not available, battery not charging, special modes not available - where before it would at least crank - now nothing. I get a click from the engine compartment fuse box. Items not working - interior lights, central locking with key, central locking with fascia buttons, head lights, boot opening, window washers, PATS alarm horn, ignition. Also getting can't apply handbrake when using the Park brake lever, hand brake is stuck on so can't tow to dealer. No lights on Gearbox selector and doesn't raise. Stop/start button does flash so def power there.

I've tried a brand new Varta battery, Voltage and SAE tested OK, same errors.

While I was waiting for mechanics to open up over the festive period thought I would check the fuel issue, lifted the rear seats, removed plastic cover and saw diesel on top of the flange unit. removed the top wiring harness plug and saw a badly burnt pin and the plug was also burnt (This is where the diesel was coming up through) as I had filled the tank. I though BINGO found the issue knowing from forums that any wiring breaks can cause havoc with multiple warnings on dash. Replaced the flange, harness and O-ring. I still have the exact same warnings on dash. I've tried reset procedure, disconnect, also touch +ve/-ve together, no change.

Yesterday, OBD scan showed multiple errors on BCM. (main ones below)
U1000-00 - Solid state driver protection activated
U3000-49 - Control Module
B1143-11 - Ignition Status 2
The rest are all the functions not working ie head lamps, fuel filler lock, wiper motors.

Also one error on GWM - B11BD-87 Battery monitoring module ---- could a blown Battery monitoring module fuse cause all this sh*t? relaying incorrect voltage info to the modules for a crank ?

Love this car guys, love driving it, but don't want to replace, replace, replace until problem solved with a hefty price tag. Any advice would be greatly appreciated chaps.