Samsung Galaxy Z Flip 4 (SM-F721B) Display And Digitizer With Frame And All Parts Purple Pulled

Problem: When the inner (main screen) has been replaced from a Flip 4, the inner screen does not work after startup. The outside screen stays on continuously.
Solution: Hold a magnet near the rear camera so that the hall sensor is activated. Update/ flash the software to the latest version (October patch). When the update is complete, remove the magnet and restart the device.
After startup, connect the device to the PC and hold down the on/off button. While holding press volume up 1 time quickly then volume down 2 times quickly and force reboot (hold volume down/ power for 15s.

To make sure it is a problem with the magnet, go to test menu (#0#) and choose hall IC. If you immediately see working pass, the screen will not work during normal use.
As a solution, heat the screen and remove the magnet from the frame shown in the photo and pass it along a demagnetizing block and put it back with a ceramic/ non-metallic tweezer. Make sure the side of the red stripe is facing up. Mount the unit and everything should work. Go to test menu to test hall IC. Working shouldn't pass right away!

In case screens stays black after repair, please remove the old sensor magnet and install on the new screen.