I’m addicted to the su doku on this thing, so I ended up back in developer mode just now, and it has remembered exactly where I was in the puzzle! Hopefully it doesn’t crash this time. I think I’ll just toggle the mode whenever I want to do a puzzle and make sure it is off the rest of the time, just in case that makes a difference.
Re the button presses, I actually did all the permutations of presses I usually do if my reader freezes, I just didn’t note them all down as I think my posts are long-winded enough already.