Thanks mate it worked. And this ROM is by far the most stable and battery saving of all I tried..Same thing happened to me because I installed the op3t open beta firmware from their download page. Once I unbricked and installed the correct firmware (there's a thread here somewhere with op3 and op3t firmwares listed, can't find it cause on mobile) it worked fine save for the usual experimental room quirks.
---------- Post added at 09:13 PM ---------- Previous post was at 09:08 PM ----------
So now I'm using Nitrogen Os with by far the fewest glitches of any Oreo room, but one minor issue I'm having is my phone doesn't seem to autoconnect to Bluetooth devices anymore. It's not a huge deal, but I like being able to take my phone in the car and it automatically connecting to my audio system.