Starting Issues??

What sort of problems? Will the engine start running or does it just endlessly crank? Did he disconnect the fuel pump inertia switch before he did the filter ot pull a fuse? One last thing,I know this sounds totally dumb but make sure he primed the fuel system multiple times afterwards.Meaning,after the new filter was installed you must turn the key on and off several times to get fuel pressure built back up before it will start.When you turn the key on you will hear the fuel pump turn on then turn back off,this is the pump detecting that the engine is not running.Its also a way to prime the system.Once pressure is back up (you will know because the fuel pump drastically slows down once pressure builds) then crank the engine.It may take a few extra cranks at first.