Bluetooth hc-06, doesn't read anything

Good morning

I'm tryng to do a simple example with hc-06 bluetooth and arduino. I have two modules Bluetooth hc-06, it works only with one of them. With the other, it writes always ¿¿¿¿¿

I have changed bauds, but it doe the same. Can anyone help me?

void setup() {
void loop() {
Serial.println("I received: ");

What does reading from Serial() have to do with a hc-06? You need to use SoftSerial on other pins. Look at the examples in the library.

If the code works already with one HC-06, I guess it is kosher, and your problem is just one of procedure. You do not need to use SoftSerial, indeed it is something best avoided.

You might find the following background notes useful.

The inverted question marks may be BECAUSE you have changed the baud rate on Arduino, but have not reconfigured Bluetooth to match. Stick with 9600 for the moment.

Look at the examples that come with the library. If you ever wish to debug your code AND use a BT module, you'll need SoftSerial.