What to expect

What's reseted:

• User data
• User installed apps
• AppLauncher mods (just databases)

What's not reseted:

• Android boot image hacks (e.g., adb)
• System roots and apps

Normal System

Method 1

Go to Settings -> System Settings -> Initialize Digital Paper

Method 2

Press reset button (tiny hole near power button) using a pin

Diagnosis Mode

In diagnosis mode, run the following

cd /usr/local/bin
./factory_reset.sh

If not working...

If you can still get into diagnosis, it is a good sign. Likely the partition is messed up, or your update script has weird issues. Further information is needed to debug this.