Have you tried another phone charger? I had a motorola charger that had a bad plug on it and it wouldn't connect right. The phone could recognize that the plug was connected, but could not route the voltage through it, thus telling me it was "unable to charge". If that's not it and another charger doesn't work either, look at the connector on the phone. See if there is any dirt or debris in it. If so, try to clean it out. Also, if you got the connector wet, it can corrode rather quickly. If this is the case, you may need to use a drop of isopropyl alcohol to clean the contacts. Hope this helps. Good luck.
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