I have had my mag 254 for several months and have not been able to use it, today while trying to do something else I discovered that my donation has the wrong Mac address. I have never used the donation, how do I change it.

Mag 254 will not up date, goes to 5% and then says" wrong signature" can I please get some help here???

I am trying to set up 254 when I try auto up date it goes to 5 and then says wrong signature. How do I fix this? My donation is up to date and mac address is correct, thanx for any help.