Ok, where should i send the board?

Yes, I have everything except USB disconnected from the Duet.

No, nothing gets hot.

No one has an idea that can help me, would be great

Thank you for your quick reply.
Yes, I have set up the Duet with USB the WIFI has worked.

Then I operated it with 24V. Everything worked fine, I could drive with the axles, switch the heating on and off, the end stops have already worked.

Only the WIFI had broken off, had to reconnect again and again.

I did not see exactly what was flashed, turned it off because of fear of destroying it. I know this is not exactly helpful information for you.

I've now removed all the cables after your tip and only plugged in the USB cable, pressed the erase button.

In the device manager of Windows, no new device is displayed, nothing new is displayed. Have already used another USB cable and another USB port.

The 3V, LED and the LED between the reset button and the USB connector are on, the 3.3V LED is off!
0_1530363851939_DSC_0003-min.JPG

I have a Duet3D wifi, I'm still at the first establishment. Could connect with the web interface already, and make adjustments. The wifi connection always breaks off. The distance to the router is about 2 meters.
I have a 24V power supply. Wanted the device to perform Duet3d via USB again, I plugged in the USB cable, I wanted to connect via USB with the Duet3D. When I wanted to make the connection, the Duet3d has started to flash about every 4 seconds a flash. I immediately pulled out the plug, then it smelled of burned electronics. Visually, I can not see any harm. Now I get no connection to the Duet3D not via USB or via wifi.
In the device manager of Windows, the Duet3D is no longer recognized.
Can you help me?