said by AnonMan :
It should stick per say because they are force telling the system that modem is that model otherwise it would never have sent any FW.
You sir, don't understand how it all works. There is no "telling" the system. When you give the MAC to the agent on the phone they enter it into GrandSlam. GrandSlam liases with other tools(BACC, etc.), your modem identifies itself and once a corresponding bootfile is found it pushes it through to your modem. If a corresponding bootfile cannot be found, that agent gets an error that tells them that there's a back end error and they can go no further. Their next step, after getting that error is for them to escalate it to a team that has BACC access and try to FORCE the bootfile on it, however, if that modem's not on the list, they'll close that ticket and may or may not call you and tell you.
Save yourself some time, just buy a new modem. Stop trying to "beat the system".