This episode was quite hard for me and I didn't enjoy it much.
I got the clue to solve the four-digit colour puzzle, but I couldn't figure out the last number until I watched the walk through. I thought it was a number derived from subtraction (5-3) rather than addition (5+3). :/
I was able to spotted some patterns under the potted plants. However, I didn't know there were buttons to press next to the drawers. There was no way to tell whether the sequence start from the top or the bottom. It'll be better if these buttons were placed directly under the potted plants.