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Hi. Thanks but te tablet was always fully charged (as far as one could tell) before trying to copy the data.
However that particular issue *may* have been solved. I decided to reformat the flash drive and start again; and discovered that despite it's large size the default format was FAT, so the reformat was set to NTFS. A following attempt to copy seemed to work ok, maybe, but I'm a bit suspicious as it went fairly fast and I'm wondering if it really transferred everything from the tablet.
I downloaded & installed a free compare programme to check but it failed to even see the tablet directories anyway, so was a fat lot of use.
The seeing the screen on an external monitor/TV requirement is still unsolved though. And a consequential issue found was that any alarms set will continue to go off, and there's no stopping them because one can't see or operate the button on a non-working screen. It auto snoozes and goes off again too.