This is a bootloader warning after unlocking. It usually appears for 5 seconds and then boots normally. To remove it, you need to re-lock the bootloader (not recommended).
Most "myviu tv box update" issues reported by users involve live channels or VOD (Video on Demand) apps like myviu tv box update
Even when you do everything right, errors happen. Here are the most frequent issues users face during a myviu tv box update. This is a bootloader warning after unlocking
Go to Settings > Apps > See all apps > System Update and "Clear Cache." you can update manually.
If your device isn't connecting to the update server or you have a specific firmware file (usually a .zip or .img file), you can update manually.