You cannot flash a custom ROM using the stock recovery. You need TWRP v3.3+ for Android 10+.
Turn off phone. Press Volume Up + Home + Power. Hold until Samsung logo flashes twice. samsung j500f custom rom
Functional, though performance may be slower on this older hardware. You cannot flash a custom ROM using the stock recovery
Disclaimer: Rooting and flashing custom ROMs voids your warranty (already expired) and may permanently damage your device if steps are not followed exactly. The author is not responsible for bricked devices. samsung j500f custom rom