Must use Setool.

1. Reinsert battery and do NOT turn on phone!
2. Start Setool and click Identify
3. Hold 2 and 5 together and in the meantime put the USB cable.
When hear that sound (though that connects USB flash memory) disconnect USB cable, reinsert battery and do NOT turn on phone!
4. Start XS++ v3.1 and click Connect.
5. Hold "C" button in the meantime put the USB cable.
6. Flash only Main, then again disconnect USB cable, reinsert battery and now can turn on phone - work fine as before.