You need to flash the TWRP recovery mate via odin then Follow hes instruction again , But you dont need to flash the modem/bootloader again. Once your done flashing the Custom recovery. Reboot into Recovery mode and make sure to make a android backup and once your done do a full wipe and Flash the Rom and your good to go.
That awkward moment when you're reading this comment and can't stop reading because you are so intrigued by it,that you keep reading,and then you realize it says nothing important.
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