Unlock the doors is the second story mission during chapter 7 in dead rising 3.
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.
While the zombies are your main enemy in dead rising 4 there will occasionally be moments where a door is standing between you and success.
For dead rising 3 on the xbox one a gamefaqs message board topic titled how do u unlocked the locked red doors.
The crates are unlocked by doing the special side.