If the MAIN is AT&T branded, you will need to use a non-AT&T MAIN file.

If you want North American firmware, you want

W580_R8BE001_MAIN_NAM_1_LA_RED52
W580_R8BE001_FS_AMERICA_1_RED52
HB1-06_Gen_CDA102568_15_R8A_GENERIC_AMERICA_1

European:
W580_R8BE001_MAIN_GENERIC_LA_RED52
W580_R8BE001_FS_EUROPE_?_RED52 (depending on what languages you want, English is standard on all)
HB1-06_Gen_CDA102568_10_R8A_GENERIC_EUROPE_?