I think I've set every error in the configuration. Therefore I want to say thanks for your help. Very appreciated.

Now remain only another problem to set on my Chiron but I think it is no more about the configuration tool. So I will discuss it in another chat. See you soon.

@dc42 What could I do now?

@dc42 yes, It's that, 1.9.1

Hi @dc42 thanks for your suggestion, I really appreciate and sorry for the delay in my reponse.
I check the tension between 3.3V and GND pins of an endstop and the tension is correct, 3.34V. What you think?

@dc42 Thanks for the suggestion on the LED Diag.
Yes, I followed the instructions about that. I can show what I did in particular:
Turned off Duet
Put Jumpering the erase jumper.
Turned on Duet for few sec.
Than turned off.
Removed the erase jumper.
Turned on Duet again.
Then pressed the Reset button.
Opened Bossa and selected COM10 and checked boxes Erase all, Lock, and Boot to flash, then press Write. The write process worked

After I clicked Verify and at the end I got the warning message (Verify failed Page errors: 1021 Byte errors: 63923) and I stoped

@jay_s_uk Since I bought it from someone else, could it be that they were added later? I believe that is original.

I said yes becouse when I received the board they were already mounted. Ma non so di più.

@jay_s_uk yes

@genioluiz7

• Do you still have the heat sinks mounted? Perhaps they are making contact and shorting something.

No, they are correctly mounted.
Have you removed the board from the case and disconnected everything except for the USB connection?

• Give the board a blast of compressed air to dislodge any debris that may be causing a short.

Ok

• Does anything get hot to the touch shortly after being connected to usb power?

No, nothing

As you can see below, I unplugged everything, and everything is clean and all the LEDs are on.

Now the COM10 is detected. So I tried the Fallback procedure #2 with BOSSA, but after clicked Write I clicked Verify and this warning message appeared.

What could I do now?

@jay_s_uk as you can see the 'diag' light is on, between the SD card and USB.

So I follow the next instruction you send me previous in this conversation:
On Duet 2, in normal operation:

• the DIAG LED will turn on as power is applied, then turn off as soon as the firmware starts loading, usually less than 0.5 second.
• In normal operation, it will turn back on if the probe type is set to M558 P1 in config.g. Removing the SD card and resetting should switch it off. Apart from this case, the DIAG LED should normally be off.
• Errors in config.g may cause the Duet to get stuck in a boot loop, which will cause the DIAG LED to be on permanently. Remove SD card and reset.
• If the reset button is stuck in (rare), or has been mounted so it is pushed in by an enclosure, the Duet will get stuck in a boot loop, which will cause the DIAG LED to be on permanently. Check there is clearance around the reset button, or use some tweezers to gently pull the button out.
• If the firmware has been erased the DIAG LED will be on permanently.

Diag LED still on

I tried also to flash it with BOSSA, with the erase pin but the LED doesn't turn off.

Now when I connect via USB the YAT software doesn't detect the COM10

@droftarts, I've replaced the WiFi module. Now what have I to do?
I post a picture of the LEDs that are on now.

@dc42 yes I tried but nothing happened. What do you think?