I Noticed that your comment was the black squares were on the second line... I also noticed the examples presented looked like they were all for the first line of your LCD.

1. Since you only have 1 line of squares on your LCD, then I would suspect your line 1 is bad... test another LCD.

2. If you want, try writing to your second line on your LCD...

I believe the command is a $C0?

Somthing like :
LCDOUT $FE,$C0,“Hello”

If this works on your second line... then you may have found your problem.

Dwayne