I’m sure the pastor wasn’t lying that the people needed new computers after downloading the Windows 10 OS, but no, he did not go into detail.
Two quick comments and an observation.
1. It's essentially impossible for an operating system to break the hardware of a computer. The means by which it might do so exist in theory, but are utterly far-fetched. The people who owned the broken computer, and the pastor, weren't lying, but likely were saying something else, to wit:
2. It might be less expensive, and certainly faster, to simply replace the computer than to repair the scrambled operating system installation. Depending on how you value your time, and in this case certainly paying someone else to fix it, you could be looking at dozens of lost hours and hundreds of dollars.
At that juncture it doesn't matter if the hardware is still perfectly fine, and even though a knowledgeable person like VanDeKoik or myself would gladly strip out the old operating system and put a fresh copy on it and be good as new, that's a path that's unavailable to a lot of people who just use computers and don't want to spend their time fussing with making them work again.
To VDK and myself, a story like yours about Windows 10 "ruining" a computer sounds like a story about a guy who drove his first car until it ran out of gas, and when it coughed to a stop, he declared it "broken" and got another with a full tank. Don't take our cynicism too seriously. :-)