Here is a 4x4 word square, which has four words reading across, and four others reading downwards, except that it is all wrong!
Precisely none of the letters is in the correct place in the grid. However, they have not been placed randomly: eight pairs of letters need to be swapped in order to solve the grid. So, for instance if you decided that the top left letter belongs in the bottom right square, that would also mean that the bottom right letter belongs in the top left square.
I can also tell you that none of the swaps are within a row or column: each letter will end up in a different row AND column from where it started.
Beware of repeated letters: even if you know for sure that a particular letter belongs in a certain square, if there are several copies of that letter in the grid, you have to choose the correct one, otherwise the other letter of the swapped pair would end up in the wrong place.
Because it is very difficult to get started with this puzzle, I will tell you one of the solution words but you’ll have to decide where it goes.
Good luck!