Random Starting electrical issues T5 2011 Diesel

[ao767brad]

I am hoping someone might be able to share some insight if they have experienced anything similar as google has lead to few leads, mostly in the UK.
I bought a T5 camper conversion (professional conversion by campervans Australia/Discovery Campers) about 2 1/2 years ago and is now 80k with full service history, that has been having random electrical issues, none of them consistent, and all with the T5 not the camper and both electrical systems are totally separated.

About 6 months ago I started having battery issues with a flat start battery every few days despite the alternator output being checked and okay, residual current drain checked with no issues and the battery being less than 18 months old and testing okay. One morning 3 months ago it wouldn't start and I used a lithium jumpstart pack as per the printed instructions and it started first try. After using the pack, the radio/satnav/reverse camera head unit did not power on. Checked all the fuses and all intact, was waiting to get time to pull the head unit out to check the fuse on the rear of the headunit. After this 1 jumpstart I hadn't had to use it again but the battery was struggling to start on cold mornings in Victoria so thinking there was a dud cell I installed a new battery 8 weeks ago. No issues since.

This morning I go to start at 5am and key through accessory to On (radio powers on for the first time in 8 weeks) WOW!! glow plug light goes off, turn the key to start and DEAD, no click, no starter motor engagement, yet the console and dash lights are on and don't dim when key goes to start. I tried back to off, remove the key from ignition and go through the process 5 times but no hint of starting. Battery fully charged. I go and call a cab for work, try it whilst waiting for cab 5 minutes later and it started first try (but no power to the radio head unit)

So every time it didn't start, the radio powered up. Every time it does start, the radio is powerless????

The local auto electrician is over it, said go to VW, the dealer can't look at it for 3 weeks and $192hr to look, google suggests
1. Possible ignition switch issue
2. Starter motor internal fault

Anyone with any ideas??

[Transporter]

Start looking into n.1 and 2 as google suggests.

[Sunny43.5]

Just a thought dissconet the battery if you haven,t already , leave it for five minutes and then reconnect . Sometimes its like a computer and needs to be rebooted , I have experienced electrical things like no power in a few different cars and the disonnect trick restored them . Sometimes the CAN Bus system will isolate a problem and it wont allow that problem to start again until disconnection or repair .

[LogicprObe]

VW will just plug the machine in and see if there is a fault list then keep trying stuff at your expense.