Problem with Arduino GSM shield

Hi,

As stated above, I have a problem with the GSM shield. I built an arduino clone from an Atmega 328, which works fine.
The deal is, when I plug the arduino gsm shield in and try to send a SMS, the power led is on, but the other two are off and stay that way. The orange capacity is also heating really much.

I connected the 5V pin, the GND pin and the reset pin to the corresponding pins on my board, and the IOREF to the 5V. Of course I also connected the RX and TX to D3 and D2.
When not connected to USB, the circuit is powered by an external power supply.
I believe the problem may be caused by the fact that I didn’t connect the 3V3 pin of the GSM shield. Do you know if it is necessary for it to work ? Otherwise, where do you think the problem might be ?

Thanks.

PS: the logic design of the circuit is attached.

EDIT: Also, here is the code:

// Include the GSM library
#include <GSM.h>

#define PINNUMBER ""

// initialize the library instance
GSM gsmAccess;
GSM_SMS sms;

void setup()
{
  // connection state
  boolean notConnected = true;
  
  pinMode(6,OUTPUT);

  // Start GSM shield
  // If your SIM has PIN, pass it as a parameter of begin() in quotes
  while(notConnected)
  {
    if(gsmAccess.begin()==GSM_READY)
      notConnected = false;
    else
    {
      digitalWrite(6,HIGH);
      delay(200);
      digitalWrite(6,LOW);
      delay(800);
    }
    // send the message
    sms.beginSMS("0600000000");
    sms.print("test arduino 1");
    sms.endSMS(); 
  }

}

void loop()
{
}

Strangely, the led on pin 6 stays off, but the led on pin 5 switches on for a couple seconds and then stays off. This happens both the gsm shield is connected and when it’s not.

logic.pdf (84.4 KB)