Updating the Samsung mobile phone operating system using Smart Switch is more accessible and safer because we can back up all data first. Errors can occur during the update, so we suggest you back up any critical data before you proceed. Available features may vary according to the function, and the features may not work correctly in some apps.
This experience occurred when I tried repairing the Redmi Note 4 Mediatek (Nickel) brick. Insert the firmware into the SP Flash Tool, and checked all partitions. However, the cust.img file has been replaced with a smaller size than the original. I tried twice with Download Only and Firmware Upgrade. Both failed, and a BROM ERROR STATUS DA EXCEED MAX NUM message appeared.
Application blocked by screen overlays detected, so it doesn't work. This problem I had experienced when I used the Lenovo A7700 Android Marshmallow operating system. Follow the message on the screen, but the application cannot be permitted. Bringing your smartphone to Safe Mode and giving permission is the best solution compared to doing a hard reset.