Please see the following link for trouble shooting:
Troubleshooting Line 6 Modeling (four-button stomp) and Tonecore pedals
If you are still having problems you will need to contact Line 6 UK for repair information:
Does anyone else find it odd that many, many, many people seem to have troubles with their delay pedals just dying out of nowhere (myself included), and all we get told is to see the troubleshooting page or are given a support ticket? Being such a common trouble, wouldn't anyone in charge know the answer to, or at least how to deal with, such an issue? It seems like the problem just gets pushed under the rug.
I have to say, I'm not very happy that my well-looked-after pedal just died like that. I wouldn't be happy if I kicked my pedal regularly and it died. It's meant to be designed to take that kind of use. As a contrast, my old Boss CE2 (weather beaten and very well used) still works like a dream, and it must be 20-25 years old or so...