LCD screen for Arduino UNO onlys shows a row of white boxes on top

Hello, I hope everyone is doing well. I am trying to use the LCD screen from the Arduino started kit to display text. I followed this tutorial exactly: [in comments] except that I plugged my LCD directly into the breadboard. The LCD came with header pins, so I didn't solder anything during this project. I am sure that all the wires work. Maybe someone can explain why there would be white boxes instead of text, so I can also troubleshoot. I also looked up other questions on this topic in this fo

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