Arduino IDE Blank Serial Monitor issue

Using RePhone GSM+BLE with Arduino IDE using Arduino IDE for RePhone Kit, LCheckSim (CheckSIM.ino) is working but LGSM (call_test.ino & sms_test.ino) not working showing just blank screen in serial monitor.
Also LBT (BTClient.ino & BTServer.ino) works sometimes only.

What could be the issue? Could the board be damaged?

Firmware updated with no issues with CheckSIM.ino & HelloWorld.ino

I believe I read somewhere that the serial monitor actually works on the alternate COM port (i.e. you load up code on COM3, use the serial monitor on COM4) but I can’t seem to get it to work myself.

You’ll also have to match the baud rates (if it’s 115200 baud in your code, you’ll have to match the baud rate in the lower right hand drop-down of the serial monitor).