I agree they where very expensive when they first came, it is unfortunate it has an issue at 5 years old. You are right, it is the relay you hear clicking on and off, the reason is because there is a short circuit on one of the circuit boards, power supply, ymain, or even the plasma panel itself can cause this. Starting with the power supply they can be found for around 100 dollars or so, A shop might cost around 225 to 250. If the Ymain and buffer boards are bad a bit more expensive 350 to 400 dollars, if the plasma panel is bad, (terminal) the panel cost more then the Tv is worth. You could contact the manufacturer to find an authorized servicer in your area I do not have access to the them out side of the US. Here is web site too where you can search via your zip code for servicer in your area. I am sorry there is no reset or easy quick fix to you up and running with this but from your explanation it needs repair by a qualified tech. Here is link you search on for service centers. Please if you need further assistance with this please reply.

http://www.tvrepair.com/canada.html