Samsung plasma has no picture but sound

Question

Hps4253x/xx model ,no picture no menu and cant see volume go up or down but sound goes up or down.I checked all inputs . What board needs to be replaced i have it open looks like 4 or 5 main c. boards all fuses are good.TV is 23 months old .Jan of 07 .the repair cost is same as buying it new , I spoke to a repairman. I want to fix it myself . if not it goes to the curb. thanks Art