OMD-EM5 is a crazy camera!

What ISO and what lens are you using, and what are you trying to do with it?

That flash has a guide number of 10 meters at ISO 200. That means that, shooting at ISO 1600, you'll get a good exposure at 14 meters (45 feet) at f/2 (what you can get with a decent prime like the 45/1.8, 20/1.7, or a $25 manual nifty fifty), or 10 meters at ISO 3200 at f/4 (which you can get with the kit lens).

It's a crappy built-in flash. It's about as crappy as other built-in flashes.