I haven't updated iOS in a while, and finally (don't ask me why…) decided to say yes to the itunes update when I plugged in. The update failed keeps returning error 53. Things I've tried:
Update iTunes and restart.
Several different real Apple cables.
…and DFU mode.
Clear caches and restart, then repeat the whole list.
I've never changed the screen or home button on this phone, and everything was working exactly normal before I clicked on the ill-fated update button.