iPad unexpectedly shutting down followed by activation - why?

Question

iPad

Hello.
I watched a movie in the morning and suddenly my iPad turned off, then rebooted, a white screen appeared, then the vertical lock screen (although I always keep the iPad in landscape orientation) marked "activation required".
I had to urgently install iTunes on the PC, I thought maybe I could reboot through the PC. But it didn't work out.

Tell me, what kind of activation and why did it happen so unexpectedly? Wi-Fi finds. iPad 2 (very first).
ZY The problem was solved))
After some fiddling with wires, plugging connectors, and other dances with tambourines, iTunes managed to solve the problem. Didn't even have to do a restore or rollback. So I don't know what I did so that after n-trying, I could connect to iTunes, enter passwords everywhere and unlock.
The only thing that is interesting is what caused this situation to arise?

Answer 1

Will it work without a sim?
It asks for a PIN code, check the SIM card on another device.