Official firmware files, especially for older or region-specific models like the S4900 series, are often provided directly by TCL Support via email or private link upon request.
Select to let the TV automatically check for and install the latest software. Contact TCL Support : Download TCL LED49S4900 Firmware part01 part01 rar
Unplug the TV, insert the USB, hold the on the TV, and plug it back in. Release the button when the LED starts blinking. TCL Support Official firmware files