Complex sentence: After a brief trial run at the diner that his father works at, his invention goes crazy after Mr. Copperbottom's boss comes in and scares him enough to make him stop what he's doing and drop some dishes which makes them break.
Split into simpler sentences: After a brief trial run at the diner that his father works at, his invention goes crazy. Wonderbot was doing a fine job until Mr. Copperbottom's boss comes in and scares Wonderbot enough to make him stop what he's doing, and drops some dishes which makes them break.