First suggestion:
Make sure the display stays on through the whole process. You can either do so in the display settings (but remember to reverse this after the update!), or you can use the “Caffeine” quick settings button (you need to edit your quick settings to use this button).
Second suggestion:
Alternatively, you can download the .zip file here to your FP6: Builds – Django REST framework (from the “url” line there) and use the “local update” option in your /e/OS Updater (note the three dots in the top right corner) after the download has completed.