Have you ever had your Device die and then refuse to charge even with the oem charger and couldnt get it to work without buying a new batt? Get an old/spare usb cable and cut the end off of it(the end that plugs into your phone) take only the red and black wires and touch them to the batt terminals ...red to + and black to - and hold for about 1 min. Then place your batt back into your device and turn on, as soon as it turns on plug another usb cable that is not cut into your device and it should start charging, it works for the blackjack and the sda and from what i have gathered most other usb chargeing phones that have this issue(seems htc is the most common culprit) here is a link to where i found this info. Hope it helps a few out like it did me.
the post is about a third the way down the page but the whole thread is informative