I solved Mini #247 in 3 minutes, 5 seconds!

⬛⬜⬜⬜⬜⬜⬛
⬛⬜⬜⬜⬜⬜⬛
⬜⬜⬜⬜⬜⬜⬜
⬜⬜⬜⬛⬜⬜⬜
⬜⬜⬜⬜⬜⬜⬜
⬛⬜⬜⬜⬜⬜⬛
⬛⬜⬜⬜⬜⬜⬛