Problem with the model TX-SR702 . Please Help .

Hello guys i am from Nepal and i had bought my Onkyo in 2005 in America, from 2008 my receiver has been giving me major problems. There is no service center here so we had given it to a good repairing center and it would work for a few days but the problem would come up again and i am totally fed up. The person said i need to get a new board which has to been ordered from abroad the CRT board. Any ideas how much it would cost and if it would be back to normal again ?? Okay so the problem is when i am watching a movie or listening to music it automatically goes to MCH or pure audio and nothing works, its just like a computer when it freezes. A few years back it wasent that much of a pain but now its become hopeless. Please your help would be greatly appreciated. Thank you .