For players looking for even more ways to earn the game's valuable treasures, Square Lock Boxes are a great place to start. Unlike some of the other treasure puzzles, this is not as simple as locating a key and clicking unlock. These boxes require the Cubic Device to open them, which includes solving a puzzle before the treasure inside becomes available.
Similar to the Wayshrines, the Square Lock Boxes are all opened with one key. While the Wayshrines were only located within the Village area, the Square Lock Boxes are only located within the Castle. This means that you will not come across any until leaving the Village and will not be able to return to get them, without a manual save, once having progressed to the Island.
Related: Resident Evil 4 Remake Final Boss & Ending Explained
The Cubic Device is an item that will be found once reaching Chapter Nine in. When completing the “Head For The Ballroom” objective that requires finding three different statue animal heads, go from the Grand Hall of the Castle to the Armory.
The Lion Head item will be here to be collected and following that, the suits of armor will come to life. After defeating them, go over to where the two centaur statues are. There is a lever on each one, pull these with the help of Ashley to open the door. Head down the corridor to the chest midway down, this will contain the Cubic Device.
Now that Leon holds the Cubic Device, all the Square Lock Boxes can be opened after solving their puzzle. When activating the Square Lock Boxes with the key, the Cubic Device will need to be positioned correctly in order to open them. Each slot on the Square Lock Box has certain protrusions that will fit in the grooves of the Cubic Device.
In order to unlock the box
Read more on screenrant.com