Hi I have a problem with my unit. The divice is fully charged as it has been plugged for more than 10 hs . All 4 blue lights Are on. Unfortunately when I connect my phone or my wife's it won't charge any of them . The lights blink all at once immediately when I plug the phones as a test but that's it. I've tried different phones and tablets and although the leds Indicates that is fully charged it won't charge any of them.