EM7455 engineering sample? Non up-gradable firmware

[nicolaus360]

I have a modem EM7455 by DELL and changed its identity to Sierra Wireless general but failed to update firmware with your script with error message. Can it be fixed ?
I used the following options as well
fdt2.exe -d 9x30 -f SWI9X30C_0 2.24.03.00.cwe SWI9X30C_02.24.03.00_GENERIC_002.021_000.nvu
sudo qmi-firmware-update
--update
-d 1199:9071
SWI9X30C_02.33.03.00.cwe
SWI9X30C_02.33.03.00_GENERIC_002.072_000.nvu
both without a success.

Hardware | manufacturer: 'Sierra Wireless, Incorporated'
| model: 'EM7455'
| revision: 'SWI9X30C_02.08.02.00 r5428 CARMD-EV-FRMWR2 2016/01

Waiting for modem in boothold mode...
Waiting for modem in boothold mode...
Waiting for modem in boothold mode...
Waiting for modem in boothold mode...
Waiting for modem in boothold mode...
Waiting for modem in boothold mode...
Waiting for modem in boothold mode...