Has sound but no picture

@jefftx proceed the same way as it was suggested in the previous question where your "question" was left as an Answer to. Proceed by following the triage chart for your model

and let us know what you find. We still need more info to see if any LED is blinking. you can also post some images of your boards with your question. Use this guide 기존 질문에 이미지 추가하기 for that. Since you have audio but no video I would concentrate on the LVDS cables and the T-Con board. Most T-con boards are fused, so check the fuse for continuity. Also, check the power board for any obvious damaged components, like domed or leaking caps etc. The number one suspect on this is the the main board followed by the tuner board. Once you remove the back cover turn your TV on and see if you can make out the backlight through some of the holes on the back of the panel cover.