Flashing will erase all data. Back up anything important. Battery: Ensure the phone is charged to at least 50%.
Even with a perfect guide, issues can arise. Here’s a troubleshooting table: nokia ta1165 firmware pac file install
Example filename: Nokia_TA1165_MT6739_SW_v3.29_PAC.zip (Note: some versions use MTK – double-check your chipset before downloading). Flashing will erase all data