Evo xfinity stuck in a loop

I all am hope some one can help me have an evo xfinity I went in to the CAS to restart my cline but it had gone not to be seen again Tried to do another one but would not have it so I did a factory reset and then put the up-to-date Software on and now it seems to be caught in some sort of loop it takes the update alright and I have tried other updates but all am getting do not turn the power off a yellow line witch normal the xbmc logo and then back to do not turn the power off a yellow again and its just repeating its self as if its in a loop