I need to download iOS 10.2 to temporarily downgrade my iphone 5s to match my version of Xcode 8 so that it will run as a device. Where can I get this? I tried iTunes backup, which explicitly stated that the backup copy would not downgrade the firmware.
Firmware, once upgraded, cannot be backed down, and none are available. Even if you found a way to replant an older version iOS, you'd end up with a franken-phone.
If you need to device-test against an older IDE, you need to find a device that has been fossilized accordingly.
I need help to unlock my iPhone 13 pro