W800i GDFS Broken

Please help.
I did what i thought i would never do.
forgot to backup GDFS and phone is a model that can´t be repaired with the update program.
I have overwriten with an GDFS from anoher phone (Stupid I know).
Have a cruiser cable.
How to repair the GDFS and get it to match the IMEI?
Need step by step instructions and what program to use.
Regards Mikael

i guess there is no free way to do that, you may try setool3box but this is for professional

you can repair GDFS by original seetools...