Sometimes OTA updates stall or fail. In that case, a manual (USB) installation is required.
The is a popular 50-inch 4K HDR smart television powered by the Android TV operating system . To maintain peak performance, resolve software bugs, and enjoy updated applications, keeping its system software current is vital. Firmware TCL 50EP660
Copy the downloaded firmware file to the root directory of the USB drive. Install: Plug the USB drive into your TCL TV. Sometimes OTA updates stall or fail
Sometimes the latest firmware breaks more than it fixes. To disable auto-updates on the TCL 50EP660: resolve software bugs
This is the official, safest method.