I have rooted my phone and installed clockwork recovery a few months a go. Now that Jelly bean is out I want to update it with a custom jelly bean rom. The problem I am having is that all the instructions that I find want me to use fastboot through the computer, which I get and understand that is the way to do it but no matter what I do, if I hold down my volume down button and then the power button nothing happens no matter how long I hold down the buttons. After I let go the phone does turn on but it goes into clockworks recovery where there is no option to enter fastboot mode. Getting really frustrated with this, have been dealling with this for weeks now wit htons of research but I am constantly hitting dead ends. Please help.