import arcpy

sheet_name = "RPN_2609"
GDB_path = r"D:Buildings_HeightCase_StudyPart_B{}.gdb".format(sheet_name)
bldg = GDB_path + "//" + "RPN_2609_BLDG_No_Zero"

with arcpy.da.UpdateCursor(bldg, ["SHAPE@","OID@"]) as cursor:
  for row in cursor:
      for vertice in row[0]:
          for pnt in vertice:
            try:
                if pnt.Z == 0:
                    pnt.Z = 1
                    cursor.updateRow(row)
            except:
                pass