I jailbroke my iphone today for the first time, it worked and then when i went to download a them it told me to reboot my device so i did, it turned off. Then it had the apple logo for an hour, from there i just held the standby key till the logo went away. Now it will only show the apple symbol and not turn on. I plug it in my mac and it shows the logo but it does not show up in iTunes!!!! I'm freaking out please help me!