Bitcoin is a magical electronic form of money, then I would shut the Power off.
Downed internet because of governments or natural disasters will stop Bitcoin...People will work immediately to bring the internet back. If the internet stops working entirely so do modern economies and governments.
Bitcoin can function even with 1% of the current nodes. Internet shutdowns, solar flares, or other disasters might disrupt a large part of the internet but Bitcoin would be secured by the part of the internet that continues to function.
The internet is adaptive–Bitcoin satellites, mesh networks, and radio transmitters can continue to transmit Bitcoin blocks and transactions between countries if cellular or fiber internet goes down
Slow or broken communication between countries can be worked around. Delays in communication between chains means more blocks are required for final settlement, but does not stop Bitcoin. If the chain split is permanent each chain can fork to disallow being rewritten.
https://safehodl.github.io/failure/#shut-off-internet-because