Problem with Pixhawk Configuration

Recently, I got a very serious problem which I cannot solve. I hope somebody could give me some advice
I now provide my procedure of setting up my Pixhawk to describe my situation.
(I want to do HITL simulation so I followed the instructions on the official website)

  1. I run my QGC and connect my Pixhawk to the computer
  2. I installed Firmware to my Pixhawk, then QGC showed my several options for setting up ( Airframe, sensors, etc.)
  3. I followed the instructions on the website, but I didn’t set up radio, power and flymodes
  4. I followed the instructions on, changed some parameters as instructed in the “PX4 configuration” part, and I clicked the button “tools” and then clicked “reboot”.

The problem is that after “reboot”, I cannot change anything of my Pixhawk anymore, the red words “waiting for vehicle connection” kept showing, and the biggest LED on my Pixhawk is solid blue. I can reinstall Firmware, but I cannot do setup anymore.

My personal opinion is to press the reset buttons and start again