If your Reader is stuck because of some bad content or screwed up files in internal memory, you should try the simple unbricking method:
1) Reset Reader (paper clip)
2) Turn it on (switch)
3) As soon as the screen flashes, plug in the USB.
4) If the Reader boots into the "USB connected" state, it should be visible on the PC. Reformat the internal memory (with Quick Format option).
If that doesn't help, your firmware may be corrupted (very improbable if you didn't flash new firmware). Then you should try the 10 reset method:
0) Unplug from USB
1) Reset Reader (paper clip)
2) Turn it on (switch)
3) As soon as the screen flashes and "Starting up" appears, Reset Reader (go to step 1).
4) Repeat this reset sequence 10 or more times.
5) The Reader should go into "Firmware Update didn't complete successfully" state.
6) Flash Reader with stock firmware updater (you may not be able to find the U.K. version, but
the U.S. version will work just fine for you).