Hello Fawkes

Welcome to the forum.

Sorry we were not here when you posted, though I see you found the problem.
This is not an uncommon problem as the cables are quite frequently mislabeled, an you have learned the first lesson in 3D Printer repair always check the cables first.
Cables on a 3D Printer are constantly moving an therefore being the weakest link the first to wear an break. second is dust and lubrication forming grit in the bearings.

We will be here.