You put an iPhone in the freezer and booted it, and that fixed it? Wow. I thought that was just for saving spinning disk drives and preserving the contents of RAM for an attack.
A cold boot means shut off all power to the device. The normal "off" button the iPhone puts it in standby mode, not off. This is so it can still listen for calls.
My iPhone 10 locked up hard a few days and I couldn’t get it to turn off using the standard method.
After some digging, I found a new trick that I guess is implemented at a lower level: press and release volume up, then volume volume down, then press and hold the main button until it powers off.
No, on the newer iPhones press and hold simply brings up Siri. Gotta press and hold main button and either volume button simultaneously. If that doesn’t work you should be able to use the trick I describe above.
