Solution to Repair the DND player quest

This is the solution for the ‘repair Faeyan DND player’ quest. Although this is not a very hard quest, the translation from russian to english of this quest is quite poor. It took me quite a while just to figure out what the hell the Faeyans even were asking me to do.

The point of the quest is to tune a DND player. This is done by checking two squares on a 3×3 square board. Each square can be either black or white. The manual for the DND player says that there are two possible tune options, either a 3×1 line or a 2×2 square of black. Your task is to check two squares and eliminate one of those two options.

The solution to this puzzle is:

Check box 2 and 8.

This seems kind of weird to me, because if the square was 4,5,7,8 picking 2 and 8 wouldn’t reveal that. This is the solution that worked for me however, so if you don’t get it the first time keep on trying with the same two boxes.