A: OTA updates preserve data. USB updates with full images may wipe everything. Always back up.
A: OTA updates roll out regionally and in batches. You can use the USB method with a generic firmware file (e.g., EU version on a US TV may work but could break tuner). Firmware TCL 502
Some TCL TVs allow downgrade via the “Secret Menu”: Press Source + 147 on remote → Enable “USB upgrade without check”. This is risky and may void warranty. A: OTA updates preserve data