I've had this ROM for a week or so now and I have to say that it's really nice compared to CM that had some annoying bugs for me. I also like that the keyboard is working very similarly to the original Samsung keyboard I had in this phone. Althoug...
Go straight into recovery after flashing. Also I recommend you to try TWRP.
Can I just repeat the first procedure in Odin on top of the old one?
Edit: I tried that, the issue is that I can't go into recovery without turning my phon...