Hold the button down until it turns off. This is usually about 10 seconds.
IF it is a newer laptop there is a tiny button hidden which you have to do this. The “Big” off button only does a minor shut down.
UNplug your internet cord or find the switch that shuts the computer in to airplane mode if there is one.
What model is it?
One of those should get you to do a hard power off.
It doesn’t sound like it is a ransom wear attack. It’s just a phony warning that took care of a vulnerability and they want you to call in to some Indian scam factory.
It is a Toshiba Satellite C55-B5101. I think I’ve had it about 3 years or so.