Thanks for that, Nathan, it was kind of what I was afraid to hear! Iv'e tried your suggestion, and can now get "Hello" as before, plus both "HDD" and the "timer set" clock logo in the display window. I think I heard the HDD run up, but there are no further indicators, or actions that the machine will let me do.
If, as I suspect, I'm going to have to buy a new machine, is there any way I can retrieve the stuff I have on the HDD?
Help so far much appreciated - I'll tip at the end!
Thanks again for such a prompt response - given that I won't be able to get the stuff off the hard drive, I guess I'll keep persevering with the on/off button!