Thunderbold update 1.2

Since two years now i will be ask from time to time to update my thonderbold firmware. But i have it already installed. I do all, what commuties wrote for solve the problem. But it does not work. I have mac mine (6th generation). I do not diconectet the power cable (how shoud i do this if the computer should run?). I did disconnect the diplay and let computer work till newstart.

Every time, th software was instaled and update searching ar negativ i thought, now the work is dann. But after a while i will be asked again for the ******* update 1.2.

Best regard

Angelo