If you debrand it you need a generic MAIN firmware too.
You must use this: W580_R8BE001_MAIN_GENERIC_LA_RED52
For the Cust pack you can use the generic of you country/language:
HB1-06_Gen_CDA102568_15_R8A_GENERIC_AMERICA_1
or a specific cust pack, but same language/country (AMERICA_1):
Laura_i_CDA102774_20_R1A_Generic_Trade_USA this for example...

W580 CDA List