how can i get a pictyre back on my deccacolour tv, model no - DF21TG6, 21"?

how do i get the telly to work, about a week ago whilst watching tv from a digi box on av2 the picture just dissapered,like someone had pressed standby, the power light was on but the tv didnt respond, about 10 min later it just turned back on. during the week it has gone from working for a few hours till yesterday when it would only work for about 15 mins every 3 hours or so. today it wont come on at all ( have checked the remote batteries and ir light with a digi cam and its fine)its like the telly is stuck in standby and wont wake up. someone has already checked inside and said there appers to be no faults on the circut board and nothing burned out ( apart from previous fixes, the on off button is broken and disconnected, and a track on the circut board burned out when that happned but has been replaced with a car fuse and a lenght of wire and has worked fine for the past 2 yrs, the scart socket at the back is also broken so we use the av connectors on the side) pleas help is there anyway to fix the tely cheaply? i can solder and de solder if someone can tell me what bits to remove/replace