Watch the ripples. They should begin after a few seconds and proceed smoothly through all strips.

If one or more strips fails to light up, check for shorts, breaks, and boo-boos. Pads can get ripped off very easily - in that case, remove and replace that strip.

If a ripple jumps around on a specific strip, it may be backwards. Adjust mapping.h to reverse it. The nodes and strips are numbered right to left, top to bottom.