Cannot flash Modem firmware

[mraposo1]

I 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 "Enable MCU Boot" checked.

Any hints?

[Martin Lesund]

Hi Mario,
Could you share the full output log from the programmer app when this happens?

Which operating system are you using?
Which version of the Thingy:91 do you have (should be mentioned on the sticker)?
What exactly are you trying to flash? (make sure it is the correct file)

Best regards,
Martin L.

[mraposo1]

Thank you. 
I was able to flash it.
It was not very clear that you have to press the big button (not the small one) and turn on the device.
Pressing the small one shows the DFUBoot device and it is a bit misleading.