Teensy 4.1 not responding

Development Boards Teensy
1

We have used for many times Teensy 3.6 and 4.1 with a custom firmware.

The Teensy are connected via USB to the PC, at this time the board is not yet used.

Using the same firmware all the 5 Teensy bougth are not working.

Not working means that we can flash correctly them (with teensy.exe) but after that they are not responding at any command.

Anu suggestion, test and help is appreciated. :roll:

2

Run through the steps here https://www.pjrc.com/teensy/troubleshoot.html and see if that and/or using the push button helps things along