ColorSageIf you have already unlocked it, you will need to use the manual method if you want to update the new firmware in the future. If the machine serial number has been removed from the FOTA server, it may need to be manually updated even if it is relocked.
Thank you very much @kikoly. Has anyone tried this? I can't understand much of that link even though I translated it. Does it recover FOTA update function? I also guess there is no way to keep DRM mechanisms.