STEP 1 - Remove all edge pieces and set aside
STEP 2 - Separate tiles into 2 piles - Style 'A' and 'B'
A Tiles - small dark square in the lower right corner / crosshatch pattern on left
STEP 4 - Attach Tiles and Edge Pieces
Since there are 2 styles, edge pieces are interchangeable and don't always match the tile pattern exactly. Correct positioning for corners shown in red.