FOR anyone installing Hyperdrive, the most probable cause of boot loop in the Walkman Music App. Don't choose it in Aroma!!!
If you already have, the only way to fix the boot loop is to ODIN back to stock, as Dark Menace suggested.
He can PM you the stock image, which you will have to flash in ODIN to successfully boot up again.
SCH-I545 - Hyperdrive
Hit the Thanks!