Use this if you have a custom ROM zip (like LineageOS 16) and a custom recovery already installed. Android 9.0 Pie Custom ROM For Tecno Spark 2 - Facebook
If you want a modern-feeling OS on MT6580: mt6580 firmware android 9 install
The progress bar at the bottom will turn yellow as the firmware installs. Use this if you have a custom ROM
Hold simultaneously until the recovery menu appears. In TWRP, go to Wipe > Advanced Wipe . In TWRP, go to Wipe > Advanced Wipe
This is a driver mismatch. You need to flash only the kernel (boot.img) and logo.bin from your original backup while keeping the new Android 9 system. Use the "Download Only" mode but only check those two partitions.
: Disconnect the phone and power it on. The first boot may take 5–10 minutes. Alternative: Custom ROMs (TWRP)