NOKIA 820. Hi All. I have had a similar problem with my nokia, 820, I am not exactly sure what I had done, ie pluged into my laptop, charging, or state of charge, but the phone screen came up with a "lightning bolt arrow, and a cog wheel" (best description I can give) No button response, so I removed the back, and battery, waited for about 5 minuets, re assembled, all ok, and has been ok for a week now. Hope this helps someone. Ray