Cant see ever see Govt ever shutting down the internet or the power grid for that would be like shooting themselves in the foot.
They would only but putting themselves in the dark.
As much as we are dependent upon the web so are Govts.
The web is hooked into everything.
Imagine the effect upon money markets? The Govt would destroy their own economy virtually overnight. How then pay the army and police?
All soldiers and police have families too.
The risk of such a crazy plan would be incalculable, meaning no Govt could possibly no fir sure how the masses would react and of course without the web online to monitor the masses then it would make their position 100 times worse.
And when you switched it all back on - how can you be certain that all systems would come back online properly and without bugs.
Honestly only a complete madman would do such a thing.

We saw what happened to the Egyptian Govt when it shut down its own internet during the Arab Spring.
Instead of it giving them control it did the very opposite.
They made themselves blind and the people took advantage.
The hackervist group anonymous helped Egyptian citizens set up a small internet network so they could communicate.
This is the real story behind the story why the Egyptian Govt fell.
The internet is much harder to destroy than people realize and thus so is Bitcoin and crypto-currency.