If you want to return to your current working state, you can dump the firmware using a serial-to-USB adapter and adb access. However, this is complex. For most users, simply saving the downloaded update file is enough—do not rely on Skyworth keeping old versions online.
To ensure the outcome, prepare correctly: skyworth 40e2000 firmware update best
Press and hold the button on the TV itself (not the remote). While holding the button, plug the TV back into the power. If you want to return to your current