Lvl 35 is about timing. I can answer that since I spent long enough figuring it out, but I wanted to ask about lvl 36 first
Lvl 36. I got the ball in the slot, which slid the door down. I tried to get a single box in there, just basic portal through the tunnel and then create a portal under a box. It seems to overshoot. I haven't gotten past that, but any info about that and further would be nice.
Lvl 35 is about timing, like I said, and requires a little setup and an idea of which buttons open which door. I did it by setting up my first portal right next to the one that opens the first door and my second one above the top left buttons . Wait for the energy ball to respawn and go through the first door. Jump through onto the second panel and then you can jump to the third one from there. The trick is with the last two. If you've set up the portals in the correct order then, you can put a portal next to the third one and go back to the top left, hit the fourth button and quickly tele to the top right and finish.