V6 Box Fault?

I have had two V6 Boxes in my property for a couple of years now - one in the Living Room and another in the main bedroom. The Bedroom box is working fine, but just over a week ago the Living Room box started randomly turning off (indication light went from White to Amber / Red) before rebooting and coming back on between two to ten minutes afterwards. This has now got progressively worse and earlier today the box did not reboot, the indication light flashed red for about 20 seconds then went off completely. I have gone through the suggested disconnection, check connections, turn back on procedure but the box no longer reboots, and the indication light stays amber. I then did the power and plus button restart as mentioned elsewhere on this forum. The light turned blue, and I was asked to reconnect to internet, whereby the software downloaded itself and the whole system appeared to have rebooted. It worked normally for two hours then lost picture, box indication went amber, then red, then went off completely.

I'm loathed to spend time going through all the restart, checking, reconnecting routine again only for the same result so I am under the impression that a replacement V6 box is needed. Quite happy to replace it myself when it arrives - just need to get one ordered. What is the best way of doing this (no I don't want to upgrade to a 360 as an option)?