This breaks my soul! Sorry you are frustrated. I believe the sequence is supposed to be, putting the red cube on the red platform first, (make sure you leave it there) then the blue then purple and then remove the blue off the platform (leave it off) and then the red (also leaving it off). That should open it. I feel like I failed in conveying what was supposed to happen, so a learning lesson for me. Thanks for reaching out.
It's okay! I really enjoyed the game otherwise. A great brain teaser, this part was just too difficult to figure out. I realize now that my first post came across a little mean, definitely not my intention. It's a great game! I'll give it another go with this newfound knowledge and post a video soon!