Flashing firmware means writing raw data to specific partitions (e.g., /dev/block/platform/*/by-name/system ). On any modern Android device (2015+), access to these block devices is strictly guarded by SELinux and Linux kernel permissions. Without root (superuser) privileges, the operating system will return a "Permission Denied" error. No amount of APK modification can bypass this unless the device is already rooted or has an unlocked bootloader with custom recovery.