iPhone stuck on press home to upgrade

First of all: I have NOT forgotten my phone passcode or Apple password. A lot of responses to similar questions have suggested recovering a passcode.

I attempted to update my iPhone SE (2nd gen) with iTunes on my Windows PC. It was stuck on the verifying update part for about 20 minutes so I cancelled the update. After that, my phone is now stuck on an all-white screen that says 'Press Home to upgrade' (similar to this and this thread). Once I press 'Home', an 'Enter Passcode' screen shows up (alphanumeric, even though the usual passcode screen and my passcode is numeric). Entering my phone passcode (which I have not forgotten) and Apple password does nothing.

I have tried restarting my phone multiple times, both with the volume up-volume down-sleep button combo and the home button-sleep button combo. I have tried doing this when disconnected to a computer, and when connected to the Windows PC where I attempted to update and when connected to my old MacBook Air. It always comes back to the white screen. Note: both computers now no longer show that the phone is connected, even when it is. What else can be tried at this point?