Regarding the OTA update, I recommend installing this APK software first. With this APK, you can now proceed with upgrading the MCU firmware version and core system applications.
Currently, you can manually check and upgrade to the latest MCU firmware version via this APK. Once the system firmware packages are uploaded, simply click Check for Updates, and the OTA app will automatically retrieve the latest version suitable for your device. Then, you just need to click Download to complete the update.