Modern devices utilizing the MT6737M chipset often come with enabled. This means the device’s BootROM (the permanent code on the chip) is programmed to reject any software that isn't digitally signed by the manufacturer.
: Many modern MTK devices have locked bootloaders; a custom DA file allows you to bypass these security checks to flash firmware, remove FRP (Factory Reset Protection), or perform a hard reset. Device Recovery Mt6737m Da File