Welcome. I am Mike, an experienced technician with more than 10 years of field experience. We are now connected together on this convenient website where I am able to help you.
In your own words, describe your level of experience with electronics- Are you "technically challenged"? or a "savvy remote control user"? or you have installed/replaced components in PC's? or maybe you can test voltages, current, resistance, and solder on circuit boards?
Because at this point the tv needs diagnosis, parts, and service. I can help you with that but with these symptoms, DIY diagnosis is going to be very complex. If you do not have the needed skills and tools then having it repaired by a local shop will end up costing more than a new 50" tv. Just an in home diagnosis is usually at least $100 up front.
Honestly unless you can DIY, you are better off replacing the tv. Especially given the current prices of tv's these days.
I'm sorry for the bad news. I do understand that finding out your tv needs expensive repairs is not pleasant but at least now you can make the most of your situation without high repair costs and long wait times. You saved a lot of time and money by coming here first.
Unless there is something else you can think of, please take a moment to submit at least a 3 star rating at the top of this page before you go.