OK, I have tried the "hold the power button for 2 secs engine running" ploy and no joy.
I have tried entering the code no. twice immediately and this is a no go, too. As soon as I enter the 5fig code my handbook holds i get "code error 1", or 3, 3 etc. I cannot input more than 5 figures at a time, as soon as I get to 5 figs entered I get the code error message.
TG, you have PM.
Interestingly, the radio serial no. generated by the method you give bears no relation to the one i think it is in my handbook (an 8 fig no preceded by BKT)