For reliable help, check threads specifically for your J2 Core model number. If you find no active builds, consider that this device has very low custom development support.
Go back to the main menu and open Developer Options . Enable USB Debugging and OEM Unlocking . twrp samsung j2 core
Go to Wipe > Format Data > Type “yes”. This removes encryption that prevents /data mounting. For reliable help, check threads specifically for your
: Transfer files directly from your computer to your phone while in recovery mode, or mount a USB drive via OTG to flash files or save backups. Telegram Messenger Essential Requirements For reliable help
: TWRP gives you the ability to wipe or format specific partitions (System, Data, Cache, Dalvik) without affecting your internal storage.