The Nokia Lumia 800 suffered from an odd bug, commonly known as the “deadly discharge” bug. Basically, the phone would completely die and refuse to turn back on if the user emptied the battery. Some people, like me, had luck getting the 800 back to life, either by playing half an hour with the charger and the power button, or with the physical hard reset.
The Nokia Lumia 900, however, does not appear to have this bug. I emptied the battery of my 900 and could easily turn the phone back on after plugging it to the wall. The 900 just displays the screen above for a couple of minutes before turning itself on. Alternatively, you can power it on manually but you will have to unplug it first.
It’s a relief that users won’t be bothered by this annoying bug, I am sure it caused plenty of returns and losses for Nokia.