Unfortunately, when I tried your sequence of actions on my device it didn't help at all. I guess it's finally died completely.

I don't think I'll be bothering to get any more gadgets like this unless they become more mass-market and can be trusted. I guess I could hassle B&Q, but the best outcome is that I'll get a replacement that'll also die (just like yours). Waste of time, really.
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zzzzap