You have more than one problem.
When a single row of blocks, similar in appearance to those in the lower right quadrant of your display, appears on the top row of the display the problem is that the display is not properly initialized. This is frequently due to a wiring problem.
If, under those conditions, the contrast potentiometer is adjusted improperly the aforementioned top row of blocks can get extremely bright and the lower row may also appear. Your display looks as if this may be happening as well.
If there is a problem with the traces on the pc board itself or, perhaps between the pc board and the display, then one half (left or right) of the display may be blank. Typically the right half would be blank indicating a problem with the auxiliary controller chip or its connections, but in your case, with the left half blank, it looks like the main controller has a problem.
It looks like you need to replace your LCD module as the first step.