Thanks Andy. Appreciated, and you were right, although there's a little more...
So for the future benefit of anyone suffering the same problem, and to save you trawling the web the way I have done this morning, here's how to fix it and get back to 'customer mode':
I suggest reading this first, because if you don't press the buttons quickly in the right order, it goes back to the error message.
1) key in 0 then engineer code then press enter (the tick), but DO THIS FAST. If you're slow, it reverts after the 4th digit. If it says "installer mode",then 2) press 99 enter (again, FAST) If it says "leaving engineering?", then 3) press enter. It will say "checking system", and should then reset back to your normal customer mode.
