I had the same unit with the same problem ("LLLL") - I emailed them a picture of the display, and then decided to call the customer service number (I was too impatient to wait for the response over a long holiday weekend). They put a new one in the mail the same day. Great service!
I ended up upgrading to the Thermapen shortly thereafter . . . ;)
Cooking on: UDS, Weber gasser and Dutch Ovens a-plenty