I have always, since I got my T2, have at least 2 backup power cables, since is no the standard PC cable ( I wish Yamaha put a decent "normal cable plug).
I found them in all computer cables and also saw some that you can use from the Radio Shack , this last ones are the "cheap" shorter, and thinner, but will do the job, some home Boom boxes use the same plug/cable type.
Long time ago happen something similar in a different instrument, and since, like you, I learn from that mistake, it will not happen 2 times.