My suggestion is to first check if the microcontroller is up running. There are a couple of things you can do to verify this, for example,

– plug the unit into your router and power it on, wait for a couple of minutes, does it get an ip address (since LCD is not working, you need to check this on the router’s configuration page, typically under Client List).
– press and hold pushbutton B2 while plugging in the USB cable, then release B2 after 1 to 2 seconds after USB cable is plugged in — does the screen remain off? At this time it should appear as an USBasp device on your computer.

If any of the above succeeds, it means the miccrocontroller is up running and the problem is most likely in the LCD. You can send an email to [email protected] to arrange for a replacement. If the above fails, you may want to recheck if the microcontroller is inserted correctly, whether the crystals are soldered correctly etc.