It's possible that you damaged one or both of the LCD controllers when you had the improper wiring. Try sending 80 characters to the display and see what happens.
Use this program as a guide:
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // put your pin numbers here
lcd.begin(20, 4); // put your LCD parameters here
for (char i=47; i<127; i++) // send 80 consecutive displayable characters to the LCD
delay(100); // this delay allows you to observe the addressing sequence