When I received this unit the battery was fully discharged, So I pluged it up and let it charge for about one hour now, can anyone tell me how to turn this unit on? I hit the on button but nothing happens? It does read on the front display that it is charging, under "fast charge" I wanted to know if the unit has to be fully charged to come on? Thanks, I'm new to this forum, any help would be greatly apprecated.