lbattraw, typically when I flash and try to get the device into usb mode, I have to hold the double box button up to 10 seconds to get it to hold. One good way to do that I've found is to hold the button with your left hand, and plug the power in with your right to boot the device (the device with boot slightly in order to go into power off charging mode). That way you don't risk letting your thumb slip off the button while it's initially choosing operating modes.