Download Oukitel C11 Pro official stock firmware from the link here, and follow the provided flashing instructions to learn how to flash the stock rom.
If you notice that any of the links provided below is broken or doesn’t work, please post in comments section so we fix and update it ASAP.
After downloading the firmware, extract contents of the archive to an empty folder on your computer. Get a functional USB cable, then follow the instructions via this link to learn how to flash the firmware.
If you have any questions or other contribution please post in comments section for assistance.