Our watch word around here is often "I hate computers", but hearing this my new one is "I hate people". Obviously someone wrote some scam that tried to convince your relative that he needed to pay some money to fix his computer. Now there is a bit of malware going around that a lot of people have heard about that encrypts all the data on your computer. And that's not this one this is just a very simple scam that hopes it will scare you into calling and paying money for no reason whatsoever.
This scam does lock up your computer and you can't type anything and you can't reboot but the answer is simple. You pull the plug your reboot is back up and everything is fine. This is actually happened to me more than once as well.
So if you get a message that indicates that your computer is broken and you need to pay money to fix it. Disregard it pull the plug and restart the computer. Most of the time that will completely fix the problem. On the other hand it can't hurt to run some software like MalwareBytes which is free software available on the web that can verify that you don't have any malware on your computer. But you should not ever pay the cash.