Go to Settings > About Phone > Software Information and tap Build Number seven times to enable Developer Options. Open Developer Options and toggle on OEM Unlocking and USB Debugging .
Click . Once completed, Odin will display a green "PASS" message. Step 2: Boot into TWRP and Format Data j400f custom rom
And that was enough.
For a stable experience, based ROMs are currently recommended over early Android 16 betas. Go to Settings > About Phone > Software
: Clean software uses less power, so your battery lasts longer. Once completed, Odin will display a green "PASS" message
The Samsung Galaxy J4 2018 (SM-J400F) is a budget-friendly device that served many users well, but as of 2026, it is officially considered "legacy hardware." Samsung stopped providing major Android updates years ago, leaving it stuck on older, slower software.
The Samsung Galaxy J400F is aging. Its hardware is fine, but its software is crippling it. By flashing a J400F custom ROM like LineageOS 20 or Project Elixir, you transform a laggy, storage-starved phone into a usable secondary device or even a daily driver for light users.