mangOH Red Getting Started failed in checking modem mode

I am new to IoT and I am trying to set up my mangOH red with WP7702. I’m following the getting started guide:

Everything has gone as the guide says. The board is connected via USB cable. When I try to flash the generic firmware from the Sierra website I get the following error:

Firmware download failed.
Primary error code: 82 - Failed in checking modem mode.
Secondary error code: 0 - Not applicable.
Device error code: 0x0 - Unknown device error code.

Hi Cju,
I would suggest you to post your question onto