EM7430 QMI devices error

you need to use the MBPL USB driver: ( MBPL_DRIVERS_R35_ENG4-usb-src.tar)

https://source.sierrawireless.com/resources/airprime/software/mbpl/mbpl-software-latest/#sthash.ZXRwiiKx.Ih35ge9z.dpbs

BTW, what is the response on these AT commands?

ati3
at!entercnd="A710"
at!usbcomp=?
at!usbcomp?

Lastly, you should use USB PID 9071 instead of 9077:

at!usbpid?
!USBPID:
APP : 9071
BOOT: 9070

OK