I managed to solve the problem for my iphone with a broken home button. I think it has something to do with the OS of your mac, it has to be a higher/updated OS for iOS 14.3 to work. Unfortunately, I backed up my data into a macOS Mojave. And it still kept going to the white screen even after updating software & restoring to factory settings.
SOLUTION #1: Update your OS
You can update your OS (mine worked on Catalina). The process of backup & restore will no longer be under “Music” previously known as iTunes. You’ll now back it up via Finder. You’ll see your iphone at the sidebar once you connect it with your USB cable.
or if this method takes too long, here’s how I did it.
SOLUTION #2: Borrow someone else’s mac with a higher OS (I used Catalina).
- On your iPhone, From the white screen, press your Sleep/Wake button + Volume Down button and long hold. The iphone will turn off and turn back on. Keep holding until you come to the Recovery Screen then let go. It should show you a diagram to connect to laptop via cable. (This takes a few tries)
- Connect your iPhone to the mac via USB cable. It won’t show up in “Music” app (previously iTunes) so don’t go there. You will find your iPhone in Finder sidebar with an eject sign next to it.
- Click on your iPhone at the side bar. It will prompt you to either Update Or Restore - Choose Restore.
- The phone will reset and will start at the “Hello” screen - Set up your iphone as a new iphone.
- Return to your own mac (mine was Mojave) and locate your backup files in your Finder.
- Click on Finder>Go>Go To Folder… OR Finder>command+shift+G
- Type in this: ~/Library/Application Support/MobileSync/Backup
- Choose your backup (named with a bunch of letters and numbers - Right click>Get Info to see the date and time it was created)
- Copy the folder to an external drive/pendrive
- Go over to the higher OS Mac, repeat steps 6-7 and paste your backup folder in there.
- Now replug your reseted iPhone into the higher OS Mac again, and click on it at the Finder sidebar.
- You will now have the option to restore your backup. The newly copied backup should show up.
- Back that bugger up. And vuala you’re done.