The visitors led 2-1 after 25 minutes. But Mellor came back to dominate the rest of the game.
Mark Oldham scored a hat trick. There were further goals from Paul Newman and Carl Bradbury and one own goal.
The side featured a number of new players; Harry Perkin, Joe Maloney, Chris Proudfoot and George Sherwood.
Mark Oldham makes in 2-2 from 20 yards
It's behind you! Paul Newman's shot goes in off the bar
Andy Given on the charge
Moston's keeper denies Luke Jubb
George Sherwood threatens on the left
Mark Oldham complete his hat trick
Moston's misery is complete as a defender scores an own goal for 6-2