Hmmm, tis ever so strange. It dies as if the battery is empty, although the battery would have, for example 70% charge left as displayed in the bottom right. It won't turn back on unless I plug it in, in which case I can turn it on straight away again and have it tell me there's still 70% left.
It's as if a battery cell gets depleted but it doesn't transition seamlessly to the next xell (not that I know how these batteries work lol).
Anyone have any ideas?
That to me sounds faulty. Plug it in to mains, power the tablet on, then put into standby mode until fully charged. Then unplug from mains and use until battery is sub 10% and then recharge. If that does not fix it your unit has a duff battery.