I used the re-flashed retail unit with no hardware modification for an hour or so.  The mini-USB supplied power.  The Avalon USB plugged into the side.  I removed one of the screws from the top of the Avalon and fed the USB cable through the slot, and mounted the TP-Link outside the case.

I later modified this unit, I removed a 0R resistor to disconnect the internal antenna, and added a 0R resistor to backfeed power from the Avalon USB connector, and added the antenna, and replaced the dead internal unit, and closed it all up.

Does the blue light stay on with your TP-Link?  If you push the reset button while it is starting up, does the blue LED flash about twice/second?
Are you trying to connect via the LAN jack?  I think the WiFi has to be configured.