SIM800L problem!!!

Hello
I have an arduino uno and a SIM800L ,but doesn’t work.Maybe the code or the circuit is uncorrect .
So I need your suggest to my problem please…
Here is the link I followed .I use a 3.7 V Li-ion battery ,3800 mAh.

#include <SoftwareSerial.h>

//Create software serial object to communicate with SIM800L
SoftwareSerial mySerial(3, 2); //SIM800L Tx & Rx is connected to Arduino #3 & #2

void setup()
{
  //Begin serial communication with Arduino and Arduino IDE (Serial Monitor)
  Serial.begin(9600);

  //Begin serial communication with Arduino and SIM800L
  mySerial.begin(9600);

  Serial.println("Initializing...");
  delay(1000);

  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  updateSerial();
  mySerial.println("AT+CSQ"); //Signal quality test, value range is 0-31 , 31 is the best
  updateSerial();
  mySerial.println("AT+CCID"); //Read SIM information to confirm whether the SIM is plugged
  updateSerial();
  mySerial.println("AT+CREG?"); //Check whether it has registered in the network
  updateSerial();
}

void loop()
{
  updateSerial();
}

void updateSerial()
{
  delay(500);
  while (Serial.available())
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
  }
  while (mySerial.available())
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
  }
}

In serial monitor ,I get the message “Initializing…” ,then I press the command “AT” and nothing happens

I have the same problem.. I use arduino uno and sim800L v2 EVB

https://forum.arduino.cc/index.php?topic=627058.0

Any picture of your connections perhaps would help

I disassemble and put back in box but connection is ok. I try sketch, it can send sms, start call, receive call but serial don't show any command I input.. I post my problem in here https://forum.arduino.cc/index.php?topic=627058.0

Try to use 5v or 3.3 v out of Arduino instead of battery. And also try to change the tx rx pins on board without changing the code.(common mistake)