Flashing a custom ROM is impossible without first unlocking the bootloader. Because there is no official tool, you must use unofficial software:
: By removing "bloatware" and optimizing system animations, you can make the modest Helio A22 chipset feel significantly more "snappy". Nokia 2.3 Custom Rom
Installing a custom ROM may void your device's warranty and can potentially brick your device. Proceed at your own risk. Flashing a custom ROM is impossible without first