Thanks again for helping me out, folks. I am so much better informed now. You know, secretly, I am kind of glad it screwed up, even though it cost me a few bad nights, cos I knew it would force me into a position in which I'd have to get to grips with the whole thing. Rather than bother anyone else needlessly, I will now go through the All In One thread and only get in touch if I there's something I just can't follow. I think I have it now. If not, back to flash mode!
Those buttons though, I have described it as best as I can above, but I'm still not 100% how I did it. So, for anyone in the same position, sure that the phone is OK, but unable to connect, just make sure you have a fully recharged battery (via the wall charger) and keeping trying.