It reads iPhone could not be restored because the firmware file was corrupt

Troubleshooting:

Turn your iPhone on and unlock it -> enter the passcode.

Go to Settings -> set Auto-Lock to Never.

Connect your device to your computer using an Apple USB cable & try also another USB cable.

(macOS) Make sure your Mac has the latest version of macOS 

(Windows OS) -> Make sure your Windows PC is up to date.

(macOS & Windows OS) Update to the latest version of iTunes.

See also -> Check your third-party security software.

Check the Wi-Fi. connection.

Turn Off Hotspot.

Turn Off or remove VPN if necessary.

Then try again to restore your iPhone.