help with equation

Minutes_Elapsed: = 
VAR startDatetime = 'Fact'[Data_Hora_Abert]
VAR endDatetime =
    IF (
        ISBLANK ( 'Fact'[Data_Hora_Fech] ) || 'Fact'[Data_Hora_Fech] < 'Fact'[Data_Hora_Abert], // WARNING: fix this to address blanks
        startDatetime,
        'Fact'[Data_Hora_Fech]
    ) 
VAR NormalRange = DATEDIFF( endDatetime, startDatetime, MINUTE )
VAR FilteredRange =
    FILTER (
        GENERATESERIES ( startDatetime, endDatetime, TIME ( 0, 1, 0 ) ),
        NOT WEEKDAY ( [Value] ) IN { 1 } // Sunday
            && NOT (  WEEKDAY ( [Value] ) IN { 7 } && HOUR ( [Value] ) >= 0 && HOUR ( [Value] ) < 12 ) // Saturday
            && NOT ( MONTH ( [Value] ) = 12 && DAY ( [Value] ) = 25 ) // Christmas example
    )

RETURN
    NormalRange - (NormalRange - COUNTROWS ( FilteredRange ) )

A friend gave me this code, but it is giving error, can someone help me?