This was not the first part of the puzzle.. I managed to get a common chest first on this one when I first pass through this.. then got the other chest...
I just went back because of the Electroculus that keeps alerting me on my map... I thought doing the relay again will do open up another puzzle that will lead to the Electroculus shown in my map..
Sorry it took so long.. good thing I went back.. I found a cube puzzle, hidden totem, and alas the hidden underground sort of Electroculus.
Hope this helps.
Thank you all for watching! Peace!