Backlight for MT-20S4A

Question

Arduino

My first experience with electronics, so I could mess up anywhere.
I assembled the circuit according to the instructions from the amp (with a correction to the datasheet of the screen that I have in my hands). I also looked at the SLY_G article - from there I made out the need to establish an R / W contact on the ground.

As a result, everything seems to be working and even the text is on the screen, but it seems that the backlight / screen is inverted: a very dark background and barely visible light letters on it. It seems to me that when I first started putting everything together, the screen shone much brighter. At first, I poked contacts quite randomly - could I ruin the screen? What else could be the problem?
Here are the pictures:

Answer 1

Apparently you forgot to connect a 10kΩ variable resistor to +5V and ground, and the center to VO (LCD pin 3). This adjusts the brightness of the LCD screen. Read more here: arduino.cc/en/Tutorial/LiquidCrystal

Answer 2

Another of the symptoms: if you pull 5v out of the arduino on a working board (leaving the ground), then the screen starts blinking. If after that you insert 5v back, then it lights up “correctly”, but immediately “goes out” for a second