FLASHING Nokia ROM ! Finding way to do it that WORKS !

I am looking for someone who knows the tricks of other methods of flashing ROMs of Nokia Windows Phones, to modify dlls or other way to do it. I need to FLASH Nokia Phone (Windows Phone 8) from one carrier to another one. Both ROM are for the same product id - but when flashing phone I have an error, verification. I have installed Nokia Care Suite - tool to flash ROMs for Nokia Windows Phones... Both ROMs are official , original from Nokia servers. I have found online that we need to modify DLL files handling process of checking ROMs... we need to bypass that... Maybe you can find other solution for that ...