4G starting screen keeps comign up , help?

every time I turn on my HTC Evo 4G , this is what happens :

- i press and hold the power button

- HTC EVO 4G appears

- sprint logo appears

-the little jingle comes up while a lot of graphic bits come together to make the yellow 4G logo

- turn black for about half a second and starts on bullet # 3 all over again.

• this is very annoying and has been doing it for a while , i already lopked up some videos and took it COMPLETELY apart and put it back together , and it still does this . can anybody help , or point me to the direction of someone who can . thanks :)