Summary
Wi-Fi broken after update? └─ You flashed KM2/KM6 firmware → reflash correct KT1 image mecool kt1 firmware
Recommendation: Stick to official stock firmware unless you are an experienced developer and accept the risks. Investigating MeCool KT1 firmware: what you need to
Path: Settings > Device Preferences > About > System Update. Recommendation: Stick to official stock firmware unless you