Here is a detailed guide on how to repair LED TVs. When troubleshooting LED TVs, always start by checking the power supply. Many issues stem from power-related problems. Next, inspect the backlight by turning on the TV in a dark room and shining a flashlight on the screen. If you can see an image with the flashlight, the backlight might be the issue.
For flickering screens, it's often related to loose connections or a failing power board. Check all cables and connections first. If the problem persists, you might need to replace the power board.
Dead pixels are unfortunately permanent in most cases, but you can try gently massaging the area with a soft cloth. Some pixel-fixing videos online can help cycle through colors rapidly to unstick pixels.
Remember, safety comes first. Always unplug your TV before opening it, and discharge capacitors properly to avoid electric shock. If you're unsure about any repair step, consult a professional technician.