09 Sprinter non-starter

[Oggy2]

Hello - My name is Iain and I’m new to the site. I’m currently in a lay-by in the Lake District in my 2009 Sprinter with a problem! This has been an intermittent issue for over a year and in spite of repair by Merc in Fareham has me stranded. Sometimes when I put the key in the ignition to start the following happens:
All the dash lights come on but then when I turn the key further to the right to engage the starter nothing happens - the lights don’t dim and there is no audible click or sound. Sometimes if I repeat this process it might start - often after several attempts - and other times, like this time, it won’t. The last time it happened and I couldn’t start it the AA came out - they couldn’t get it going either so they took it to a MB garage. When they tried it started with no problem but after I described the problem they change something in the ignition switch which they said was causing the problem (£600) pounds later and I’m stuck again!
I’m reluctant to call the AA as if they can’t fix it at the roadside I will have no option other than to be relayed home and we’ve only just got here. I’m wondering if it may be solenoid related and wonder if I could run a jury cable to the starter motor using a jump lead to see if it starts?
I’m sorry this post is so long but I would be very grateful for any help that anyone might be able to give me.

Thank you for reading this

 

[m80]

Not familiar with the Sprinter, but see some equipment is shared with the 639 (Vito).
As a simple test you might look into the fuse box under the bonnet.
Embossed is possibly the number A639 545 08 --, if you're lucky.
I see 2 relays 'may' cause your issue, K4 or K8. These are grey relays to the top left of the fuse tray.
Try giving them a tap while the ignition is on, in case it's a pitted contact.
Then try a start.

Be cautious as water in there is terminal for the electronics.