Vestel uses locked MediaTek (MTK) chipsets. The bootloader is cryptographically signed. There is no known public exploit to unlock it. Your only options are:
A: No. Vestel non-Android TVs have no OTA (Over The Air) consumer update mechanism. You must use USB. vestel firmware
In 2017, the story of Vestel firmware took a dramatic turn when security researchers from AV-Comparatives Vestel uses locked MediaTek (MTK) chipsets
Official sources are nearly nonexistent. Vestel supplies firmware directly to rebranders, not consumers. Your best sources: vestel firmware
Community firmware voids warranty and kills the TV tuner. Only for hardware hackers.