ECU

You could have a bad ECU or wiring between the DLC and the ECU.

Try using a different scan tool to see if it works.

Fuses provides power supply to the ECU amnd DLC, so if you have a power supply fault, the scan tool would not work.

It sounds like there is a conflict on the communication bus. If one or more computers cannot communicate with each other, you need to disconnect one at a time till you can communicate. This is best donen by a shop that is expierenced with this diag.

Roy

You have around 5 or 6 computers in your car. These control units all talk to each other and when one cant talk, a communication error starts. It is hard to say which one being as I cannot touch the car. Locating each unit and disconnecting the power will disable it and thats how you do it. At the aldl connector, there should be a certain voltage on the communication bus line. It needs to be checked as each unit is disconnected.
This is why I said you are better off letting a shop help you as they have the expierence with these diags.

Roy