The power supply board turns wall voltage into the several DC rails a TV needs. When it fails the set is usually completely dead, or it clicks and shuts down a few seconds after switching on.
Look for bulged capacitors, burnt resistors or a blown fuse before replacing the whole board, and always confirm the part number against the label on the original.
A power supply that fits physically but is rated for a different panel size will either refuse to start or run hot. Match the board number, then confirm the connector layout matches the photo.
