1st gen IPad apple logo flashes 6 sec on/3 sec off when plugged into the charger.

1st gen IPad apple logo flashes 6 sec on/3 sec off when plugged into the charger. Tried hard reset, no good. Tried to connect to iTunes thru my computer, but the moment it is unplugged from the wall charger the screen goes black. Computer does not recognize it as being plugged into the USB port and ipad screen is black. What’s going on?