Samsung devices require an unlocked bootloader to accept custom partitions. Power off your device completely.
Since you disabled Auto Reboot, your phone is still in Download Mode. Hold to exit Download Mode. twrp samsung j2 core
Tap seven times until "Developer mode has been enabled" appears. Go back to Settings > Developer Options . Enable USB Debugging . Samsung devices require an unlocked bootloader to accept
The bootloader unlocking process will factory reset your phone. Charge Your Battery: Ensure you have at least 50% power. twrp samsung j2 core
Access internal storage even when the OS won't boot. Prerequisites and Safety
A warning screen will appear. Long press to enter device unlock mode. Confirm the unlock. Your device will wipe and reboot.