Unlock doors dead rising 4.
Unlock locked doors dead rising 3.
The locked doors are all accessed by completing the main story and side missions which will give you access to all collectibles.
Unlock the doors is the second story mission during chapter 7 in dead rising 3.
Doors are normally unlocked by either finding an alternate route and opening it from the other side or completing side missions.
For dead rising 3 on the xbox one a gamefaqs message board topic titled how do u unlocked the locked red doors.