Debunked: Can iPhone calls (or 5G) start fires or fry your brain?

A recent viral video uploaded on YouTube and Twitter is claiming that iPhone calls can be dangerous to our health. In the video, someone placed steel wool around what appears to be an iPhone 6. When an incoming call starts, the surrounding steel wool instantaneously ignites - according to the video's title, this is "how your iPhone will damage your brain."
To be clear, there is no way in which an incoming phone call can start a fire, be it on 5G, 4G, or any other wireless technology. Our colleague Nick used some steel wool to test this, as you can see in our own video below. We did manage to easily set the wool on fire, but not because of an incoming call.
Yes, phones can overheat, but...
Now, you've certainly seen cases of iPhones and Android smartphones overheating, or even exploding. But, in the rare instances when a phone catches on fire, faulty batteries and hardware are the culprit.
Current 5G phones can overheat when data is downloaded - as WSJ notes here - because 5G modems require more power than modems using older wireless technologies. When that happens, the handset automatically switches to 4G to cool down and keep things on the safe side. But this can (and hopefully will) improve with more attention given to the design and inner thermal conduction of 5G devices.
Meanwhile, here's a closer look at 5G and why it's not the brain-frying technology that some say it is.