How to request new dvr, mine will not reset or respond to remote

Received new tv, and after triple checking connections, tv says no signal, check connections.  Dvr & gateway reset multiple times- dvr has all 3 lights on green/blue/red and they do not react to reset or by trying to power off manually or with remote.  Dvr is about 8 years old, and after 6 hours of troubleshooting, I believe it is not going to function again.  How do I request a replacement dvr?  Help!