Hi There, New to 3D Printing

I created a model on SketchUp and went to Makerbot to have it printed. Unfortunately, nothing came out and was told that it was because my model still had open faces. I then tried other programs like MeshMixer, which was recommended to me by the guys at Makerbot but still, nothing comes out. I'm wondering if there is a program or a plugin to a program that can automatically detect and identify open faces in 3D models. I have tried countless times to go over the model but nothing seems to work and I am at a loss on how to find them

Regards