As you learn more about robotic maze-solving mice, break up the problem into its component parts.
What is a maze solving mouse robot made of? A system for locomotion (further broken down to motors, motor controller), a power system (batteries, power regulators) ... what else?
When you take a complex problem and split it into smaller, easier problems, you can then start to tackle one little thing at a time. So, pick one of the components and get that working, then add the next, and the next.