Hello all,
After lot of reading comments and googling, I had left all hopes and was looking for a new TV replacement. But I took a chance to open the back panel and searched for WiFi module which was right next to power button. Just unplugged and blown a bit to clear some dust and plugged back in. And my TV was like new again. All problems solved. I am using lg 49sj800v. Try this before you make some hard decisions.