Samsung LNT4671FX/AAA - no picture, but have audio. HELP!

i have a Samsung LNT4671FX/AAA. this morning i tried to turn the tv on and all i get is a small jingle and no screen. i have audio, but a white screen. here is what i've tried already. 1. swapped out the surge protector. 2. unplugged the unit for one hour and tried it again. 3. swapped out HDMI cables. 4. swapped out cable boxes with another one from my house that works. 5. tried changing HDMI inputs. i've also noticed that the Source light is blinking above the Menu button. any thing else you can think off. could it be that the main board went? would i still have audio if the main board goes? thanks for the help.