The safest way to update is through the TV's menu or official support channels:

Release the button when you see an "Upgrading" message or a blinking LED. Do not turn off the power during this process, which usually takes about 4 minutes. TCL LED43S4900 Key Features This model is a Full HD Smart TV launched in 2017.

Contact TCL Customer Support to request the specific .bin or Update.img file for your model if the online update fails. 2. How to Handle Multi-Part RAR Files

Press and hold the physical power button on the TV (not the remote). While holding it, plug the TV back in.