Starting after 12 v battery has run down.

[Markl]

After leaving the van for about 3 weeks I was surprised to find the 12 v battery flat. The battery that moves the vehicle is still on 98%.
Any way, 12v battery now charged but engine will not start. Under warranty so will probably have to ask VW to send someone out but wondered if anyone else has had similar issues and how they solved it?

 

[WelshGas]

After leaving the van for about 3 weeks I was surprised to find the 12 v battery flat. The battery that moves the vehicle is still on 98%.
Any way, 12v battery now charged but engine will not start. Under warranty so will probably have to ask VW to send someone out but wondered if anyone else has had similar issues and how they solved it?

How did you recharge the 12v battery?
Have you tried jump starting as per the instructions in the Handbook?