what is wrong with my TV?

I have a RCA 52"hdtv m#D52W17) It just went blank while watching it no sign nothing was wrong before hand. No sound No picture but power light is still on. when it happened it started making a popping noise like electric so I unplugged it when my husband came in I told him what happened so he looked at it and found where the popping was coming from. a black box at the edge of the computer board about 4in long and maybe 5in wide not part of board just attached to it it has a focus & a Screen nobs on it . What is it? and can we fix it @ home ? It is only 11 months old