How To Repair Broken Di2 Wire without Removing the Bottom Bracket

I recently damaged the electrical wire from the Shimano Di2 rear derailleur whilst on a bike ride, the only way to replace the wire is to remove the bottom bracket, i didn't want to do this as the bike is only a couple of years old so i decided to repair the exiting one instead. This is a whole lot easier than removing the bottom bracket, i'll put a new wire on one day when i need to the bottom bracket but for now this will be fine.