I can’t answer the question on failure, but there is no GRUB in an embedded system. It uses U-Boot instead. Since there is no BIOS/UEFI for embedded the bootloader must handle all of the content the BIOS would normally set up.
In terms of the actual error I’m sure whoever answers will want a serial console log and dmesg content to narrow down the issue. Video failure can never be used as a sign of boot failure, but it sounds like you have an actual crash message.