Cellular radio dead? No carrier signal, "No service", no mobile networks

I own a Motorola Moto G 4G (XT1040). Original stock ROM, Android 5.1, unlocked bootloader, custom TeamWin recovery, rooted. I only install apps from Google Play, F-Droid or trusted sources. Last week, a strange issue appeared out of the blue -- I haven't flashed any new roms, recoveries, nothing out of the ordinary, just my normal daily usage like the last entire year. Until then, I had been using the same retail stock ROM it came from factory, without ever flashing any other ROMs. (I have had this very same issue before once, with exactly the same symptoms, but I can't remember what I did in order to fix it - however the fact I was able to fix it could mean it's not a hardware issue. Maybe. Who knows). The mobile signal icon started displaying zero bars, and a "no service" message: I can't make or receive any calls, or use mobile data, despite a "G" icon that, I think, indicates some sort of data connectivity. # I've already tried: - Enabling and disabling the airplane mode, - Rebooting the device, - Changing the "preferred network mode" to either 2G, 3G or 4G, - A factory reset, - Installing CyanogenMod 13.0 latest snapshot, - Restoring a known good TeamWin full backup (which includes the modem partition) I've performed adb logcat -b radio -v time -d and it includes the following line: 12-13 03:42:01.520 D/RilRequest( 1653): A bad SIM card - My SIM card works on another phone; 1. A blacklisted IMEI (**very** unlikely) - according to random sites , there's no block.