Pixhawk 2.4.8 blue led and no power led

Hello, I need some help.
We bought a DIY Drone Kit from QwinOut as a hexacopter and it came with a Pixhawk 2.4.8.
I’ve tested the pixhawk connecting it to the PC and everything was ok.
So as a next step, I followed the instructions of the vendor to start for the first time, as the image below. In the step 3, the pixhawk stoped working, and now just have a blue led on it.
Anyone has a tip on how to fix this?
Thanks.