My lcd1602 doesn't work correctly

Using Arduino Displays
1

I make an electronic safety by arduino nano. I simulated it on Wokwi and it worked as I expected. When I built it and uploaded the code, my lcd sometimes worked but mostly it displayed black boxes or weird characters and could not interact with my keypad anymore. Additionally, my nano could not remember the code when I charged it with other power supplies such as power bank.
Can somebody help me please and thank you for your help.
Here is my code:

#include <Keypad.h>
#include <LiquidCrystal.h>
#include <Servo.h>
//keypad here
const byte rownum= 4;
const byte colnum= 3;
byte rowpins[rownum]= {A0, A1, A2, A3};
byte colpins[colnum]= {8,9,10};
char keys[rownum][colnum]={
  {'1', '2', '3'},
  {'4', '5', '6'},
  {'7', '8', '9'},
  {'*', '0', '#'}
};
Keypad keypad= Keypad(makeKeymap(keys), rowpins, colpins, rownum, colnum);
//LCD here
LiquidCrystal lcd(2,3,4,5,6,7);
//Servo here
Servo servo;
int pos=90;
//locking code here
String SecretCode= "1236";

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  //setup for lcd
  lcd.clear();
  lcd.begin(16,2);
  //setup for servo
  servo.attach(11);
}

void LockScreen(){
  lcd.clear();
  lcd.setCursor(4,0);
  lcd.print("Locking");
  delay(2000);
  lcd.clear();
  lcd.setCursor(2,0);
  String entercode="Enter code";
  for (byte i=0; i< entercode.length(); i++){
    lcd.print(entercode[i]);
    delay(50);
  }
  delay(2000);
  lcd.clear();
  lcd.setCursor(2,0);
  String toverify="# to verify";
  for (byte i=0; i< toverify.length(); i++){
    lcd.print(toverify[i]);
    delay(50);
  }
}

void Lock(){
  pos=0;
  servo.write(pos);
  delay(200);
}

void Unlock(){
  pos=90;
  servo.write(pos);
  delay(200);
}

String Enter(){
  lcd.setCursor(2,1);
  String enter="";
  char key=keypad.getKey();
  while (key!='#'){
    key=keypad.getKey();
    if(key >= '0' && key <= '9'){
      lcd.print(key);
      enter+=key;
    }
  }
  return enter;
}

void Verifying(){
  String code=Enter();
  delay(500);
  lcd.clear();
  String verify="Verifying....";
  for (byte i=0; i< verify.length(); i++){
    lcd.print(verify[i]);
    delay(100);
  }
  delay(2000);
  if (code==SecretCode){
    lcd.clear();
    lcd.print("Unlock Succeed");
    Unlock();
    delay(3000);
    Locking();
  } else{
    lcd.clear();
    lcd.print("ACCESS DENIED");
    delay(3000);
  }
}

void Locking(){
  lcd.clear();
  lcd.setCursor(2,0);
  lcd.print("* to lock");
  char key=keypad.getKey();
  while(key!='*'){
    key=keypad.getKey();
  }
  if(key=='*'){
    Lock();
  }
}


void loop() {
  // put your main code here, to run repeatedly:
  if (pos==90){
    Lock();
  } else if (pos==0) {
    LockScreen();
    Verifying();
  }
}

Here is the circuit made on Wokwi.

Screenshot 2024-08-10 174607
Screenshot 2024-08-10 174607820×862 51.6 KB

3

grafik
grafik1920×956 118 KB

4

I am quite sure that I connect my curcuit correctly as same as the simulated diagram because sometimes it worked. But when I unplug and plug it back to the same computer, the circuit get into trouble again, displaying weird characters and black boxes.

5

yeah, like that but the lcd doesn't work quite well in reality.

6

are you able to replace it?

7

replacing which component? if you mean that I should replace nano with uno r3, I just cannot because I ony have nano and I tend to make a small electronic locker.

8

when LCD is damaged(bc we are sure you connect every wire properly) you can build small locker without screen.

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