SIM unlock and Hard reset
2 things: SIM unlock and Start in Safe Mode
I believe you may need a Docomo SIM to do this, but it doesn't hurt to try with a non Docomo SIM. (please post results)
Open your phone dialpad and enter *#*#4669#*#* to get into the unlock menu.
The unlock code is 5e589dBXYfDGef9ba3dZBDE6
With the power off (not reboot), press and hold the menu,back and power button at the same time until fully booted. You should see a box in the left bottom corner saying "Safe Mode".