Help Can you disable mobile/load other firmware?

[greycobalt]

I got this from someone off Craigslist tonight after my N7 2013 died on me the other day. Got a great deal on it, but it's from AT&T, and I have no intention of using mobile data on it. The giant SIM notification telling me it's missing, and the reception bar with a huge X are really starting to annoy me. Is there any way to get rid of this? Or better yet, is it possible to install the firmware from the WiFi-only version instead, or will that make it start melting? Any help would be greatly appreciated!

Also, wow, I didn't think I'd be able to notice the comparatively low-res screen, but it's super noticeable!

 

[Dngrsone]

I have my old phone set to Airplane mode, though I suspect you could probably do something with a third-party ROM...

 

[greycobalt]

Yeah, airplane mode gets rid of the network bars, but the SIM warning is still there and on the lockscreen. I've posted on XDA about ROMs, but haven't gotten an answer yet.

 

[Dngrsone]

That's probably the best place for this question... do let us know what you found out, though.