Well I flashed Slim Rom, and was able to get into *#*#4636#*#* to change radio band. Tried them all, no change.
Played around with the preferred networks and no luck either.
I'm officially out of ideas, but I'll keep digging around to see what I can find.
Any suggestions welcome.
Also, I know that there is a known issue with the GPS signal on some Nexus 5, and there are a few videos on Youtube showing how to fix it (basically opening the back of the phone, and sticking a piece of paper under the connector).
Does anyone know if there is something similar happening with the radio? Does anyone have a photo of the phone showing which part would be the antenna?
One additional thing I noticed.
If I switch, or just take out and reinsert the micro sim, the phone asks for a reboot. After doing that, when the phone boots up, I see I have network (full bars), going into mobile operators, I can see my carrier, and I can register too. But I cant make or receive any calls or messages.
During this 10 minutes that I have this sort of fake signal, if I go into *#*#4636#*#* and phone info, I can see my carrier, but it doesn't show my phone number. Weird.