I spent (wasted) over two weeks trying to install the CS OS 4.x on the RPi 4B. I tried versions 4.0.2 and 4.0.3. Without success.
I described my problems in other topics.
I ported the same SD disk into RPi 3B, and it started without problems.
Conclusion: there is a problem with this board.
I won’t try to install CS OS 4.x on this board for a long time.