1. You can press the stars to see how many times they flash. Starting from the upper left, going clockwise:
2, 4, /5, 6, 7, /9, 10, /11, 12, 1
If you press too many stars, you will fail and have to restart.
You will see that the numbers missing are 8 and 3 (from the stars flashing).The 3 is on the top wall between the two stars (2 and 4) and the 8 is on the bottom wall on the far right.
If you look at the roman numerals, that is showing the total number of flashes of all the stars on that wall.
This can help you find the missing numbers as well.
2. You can see that the 3 on top is the planet with a long light beam. This represents the long hand of a clock.
You can see that the 8 on bottom is the planet with the short light beam. This represents the short hand of a clock.
This means that the time is 8:15. Press the circular symbol next to the door and put the correct dots to make 8:15 (8 on the left, 1 in the middle, 5 on the right).