Wait for a progress bar or "Software Updating" screen to appear, then release the button.
When your TV is unresponsive, a standard System Update via the menu isn't an option. Instead, you need to "flash" the firmware using a USB drive. Download 35017861 1920x1080 Konka KDL55XS715AN part4 rar
: The 35017861 firmware is designed for models with a 1920x1080 resolution panel. It fixes "boot loops" where the TV won't start past the loading screen. Wait for a progress bar or "Software Updating"
Official firmware can be difficult to track down. You can check the KONKA Support Center for official regional releases, or specialized repair forums like Elektrotanya for service manuals and schematics. Download 35017861 1920x1080 Konka KDL55XS715AN part4 rar