stuck on overheat screen

My Nikon Flash - SB 700 Speedlight has been stuck on the overheated screen or thermal cut-out indicator screen for over a year now. I just just turned it on last winter randomly and it was on that screen. It never got overheated to start. I rarely used it and took super good care of it so this seems incredibly unfair. I assume it just needs to be factory reset, the problem is, you cant do that without accessing the menu. I have contacted a camera repair place and they said they cant do anything because Nikon only lets their products be repaired at thier centers. However, Nikon wont tell me how much its going to cost me before I send it in (where I am responsible for the shipping there and back). Can someone please tell me how to fix myself or how much it will cost just for a factory reset? I cant find anyone else having this issue anywhere on the internet! thanks.