I returned from holiday and saw the wing mirrors were unfolded and doors unlocked on my 20 series 2009 Vellfire. The keyfob did not work to lock it and the battery seemed flat, which is odd as its only a few months old. I'm certain I locked it before going on 2 weeks holiday, although there is a light in the boot area that can be switched on when the ignition is off and so could drain the battery. I doubt the vellfire would unlock itself in the event of a dying battery, though.
I used a lithium battery jump starter (normally works instantly even with a damaged battery) and the electrics of the dashboard flicked on and off a few times before dying with quiet ascending electrical noise (maybe a signal through the audio system). I tried it a few times, but couldn't get it to turn over enough to start during one of the brief moments of flickering on. Doesn't quite match other people's description of the Immobiliser being activated.
Can't see any evidence of anyone having stolen anything, or moved stuff around. No evidence of forced entry on the locks/outside the vehicle. We get scumbags checking for unlocked car doors at night/early morning and taking sat nav screens, money, and other items, but no break-ins. Sometimes, houses have been broken into and fobs taken to aid stealing of a car. No evidence of house being broken into and the fobs are all present.
I thought I'd share in case anyond else experienced similar issues. I will try removing and charging up the battery and see if that helps and update my progress as I try to get it back working again. It has been running perfectly since I replaced the battery in March 24, even with the previous damaged battery, the jump starter aways worked instantly whenever needed.
Wish me luck!
Update:
Battery tester showed just 1.5v. Hooked up a battery charger and the dashboard came to life and remained on as it charges. Keyfob recognised, but not enough power to lock/unlock with fob. The start button worked to turn on the power, but I leave the battery to fully charge before trying to start the engine. The central locking worked from the door switch and the window would slowly open and close. Looks like the electrical system is okay. I've switched off and locked up whilst the battery charges up. Feeling optimistic 😌