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!

 

[B. Diddy]

If you turn on Airplane Mode, do those warnings go away? You can still turn on wi-fi while in Airplane Mode.

 

[greycobalt]

Yeah, I tried that. :-/ The network bars go away which is nice, but the SIM card warning still stays in the notification bar and the lock screen.

 

[B. Diddy]

From what I could find on the web, you may have to root the tablet if you want to get rid of that notification: root - Remove "No SIM Card in Phone" message - Android Enthusiasts Stack Exchange

 

[greycobalt]

Rooting is fine with me too, I was hoping towelroot would work with it, but it did not. I'll have to look into it. I was hoping I could load the WiFi - only firmware, but I feel like that wouldn't work well.