I have repositioned the Hbridge from inside the body to the outside for better cooling. I notice the cup holder area getting quite warm after running Roli around on the floor. The external mounted Hbridge now can radiate more effectively.
Add some extra length to the motor wires with the same or larger gauge. The other wires to ezb4 are already long enough.
Be very careful not to touch the Hbridge fins as they get very hot and will burn the skin.