Unlock it? Do you mean you're trying to uncap the modem or are you trying to edit the firmware and passworded yourself out?
If you're trying to uncap the modem, I honestly wouldn't bother, USB limits out at about 4 megabits per second which you'll reach easily without uncapping it. The reason it limits out like this is because the bus speed, which is gonna limit you pretty severely
This is at least my experience with the USB1/2 modems, I don't know if there are any USB 3 modems, but I doubt they would be any faster.