Thanks, igorsk. And you are absolutely right, reset on its own, holding the pin in place for ten minutes or half a second, makes no difference. Will remember about toggling the power switch.
Another point I have read since is that print on the screen takes no power. I had been waiting for the power to run down. If it's right that there is no power drain once the screen has the print, then I would have been waiting a long time.
igorsk, I see you have the 505. The most disappointing aspect of the 500 is its inablity to make much of pdf files. I have so many tutorials in Acrobat format, and that was the reason I bought the reader.
I have read that pdfs work properly in the 505. Is that true in your experience? I thought that I should try to trade my 500 in on a 505, if they really can handle a pdf. Be very grateful for advice.