https://devzone.nordicsemi.com/f/nordic-q-a/67035/cannot-flash-modem-firmwareI go into MCUBoot mode and I get: MCUboot DFU failed. Error occured when program. Errorcode: CouldNotOpenDevice (0x4) Lowlevel error: Unknown value (ffffff8e) When trying to program. I have &quot;Enable MCU Boot&quot; checked. Any hints?en-USTelligent Community 13Tue, 13 Oct 2020 18:11:31 GMThttps://devzone.nordicsemi.com/thread/274736?ContentTypeID=1Tue, 13 Oct 2020 18:11:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f587dfb0-5ffe-4234-9fdc-c4e5f8b8e080mraposo1<p>Thank you.&nbsp; <br />I was able to flash it.<br />It was not very clear that you have to press the big button (not the small one) and turn on the device.<br />Pressing the small one shows the DFUBoot device and it is a bit misleading.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/274705?ContentTypeID=1Tue, 13 Oct 2020 14:20:04 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6fe373e0-4b98-4365-8a5e-38aa64fd7fd1Martin Lesund<p>Hi Mario,<br />Could you share the full output log from the programmer app when this happens?<br /><img src="https://devzone.nordicsemi.com/resized-image/__size/320x240/__key/communityserver-discussions-components-files/4/8484.pastedimage1602598677954v1.png" alt=" " /><br />Which operating system are you using?<br />Which version of the Thingy:91 do you have (should be mentioned on the sticker)?<br />What exactly are you trying to flash? (make sure it is <a href="https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nc_programmer%2FUG%2Fnrf_connect_programmer%2Fncp_pgming_thingy91_usb.html" rel="noopener noreferrer" target="_blank">the correct file)</a><br /><br />Best regards,<br />Martin L.</p><div style="clear:both;"></div>