Sylvania TVs are disposable. Warranty is 90 labor, 1 year parts. Toss it, it'll cost more than the unit's value to repair. 8 Years is pretty good for an inexpensive TV. you could check with a local repair center to try and locate a replacement main board. At 8 years, parts aren't usually available though. Might try ebay if you are willing to replace it yourself.
Thanks jcoultas! Failed to mention Olevia went bankrupt a couple of years ago. Will go the way of the Sylvania. Have a great week!