Cheers for that Kingpr - this is sort of what I was suspecting.
The kind people from Kobo have responded to my email overnight (
the email where I clearly stated that I'd gone down the +volume then switch on route.) They've given me instructions to do exactly that and to contact them if that doesn't work.
I do love it so much when people don't take notice of what you're telling them! NOT! 
I'd left my Vox with it's green light flashing the night away last night to drain the battery in the hopes that a fresh recharge and restart might work so I'm now having to charge it again to try one last time to restart it via this route.
In the instructions from the kind people at Kobo it says that I have to hold down the +volume button until the reboot starts. I wonder if I'll still be holding it when I nip down the shops later today to buy something that is actually useful and not a pile of junk!?
I'm not yet decided what I'll spend my money on - but one things for sure - it wont be a Kobo of any sort!
Ench