If the hardware was in a funky state, sometimes it can get "stuck" in that state until a real power-off situation. The device never really powers off completely unless there's no battery in it for a while. There are at least a couple of issues that are only correctable by removing the battery, pressing the power button a few times, and replacing it. GSM and wifi hardware tend to have this issue more than others because the drivers are closed-source, so the kinks/bugs can't be found/fixed.