I have installed CM 10.2.1. on my Galaxy s4 Sprint and after installation it is stucked in boot loop. I tried ti press down, home and power button together but it doesn't take me to recovery. It takes me to some strange screen where says: Warning! A custom rom may cause problems and so... If you want to download custom ROM press up key, else (to reboot device) press down key. When I press up key it takes me to ODIN MODE, where says downloading... When press down it reboots and cm boot loop starts again... I really need help, I'm not sure what to do, I couldn reboot it to recovery from cmd because I'm unauthorised... What else can I do..? Thanks..