Hi everybody! I had the same problem with my iphone 6 and a broken home button. My iphone storage is full and I want to reset it. I've done a backup on itunes and about to restore it. The first "hello welcome" screen requires a home button to continue. I managed to get past it using 3utools to add assistivetouch via accessibility settings. While restore process is running, I left it. At that time I made a passcode lock and when I came back, the screen was stuck on the "Press home button to upgrade". I couldn't press the assistivetouch that was there. After searching and doing various ways on the internet, I managed to solve it by flashing recovery mode (idk what it calls) and repeating the process restore without adding passcode. You can do flash recovery mode via reiboot but it is paid and I did it via 3utools for free.