The author and this blog are not responsible for any damage or issues that may arise during the installation process. Proceed at your own risk.

In TWRP, go to > Advanced Wipe and select: Dalvik Cache, System, and Cache. Flash ROM and GApps : Go to Install and select the Android 7.1.2 ROM zip file.

The device feels incredibly slow after a month. Solution: The eMMC storage on the P5110 is old and slow. Go to Settings > Storage > Cached data > Clear. Then reboot into TWRP and wipe Dalvik/ART Cache only.