Hi! I just got my Hyperpixel 3.5" yesterday, and am excited to see what I can do with it. I’m hoping this is just something that a RPi noob like me is overlooking.
Unfortunately, the screen is dim during the boot up process and on the desktop on my Raspberry Pi 3. I thought maybe I had something off in my Raspbian installation, so I re-flashed the Micro-SD card with the 2018-03-13-raspbian-stretch.img file. Then I performed apt update and apt upgrade, then ran the hyperpixel installation script from curl and rebooted. Still got the same result. I unseated/reseated it on the GPIO header thinking maybe something wasn’t making good connection. Same result.
I thought it might be a backlight problem, but I can see light around the edges of the screen. The RPi boots fine, and will get to the desktop, but it hard to see it. If I comment out the Hyperpixel entries in the config.txt file, I can reboot back to my HDMI display.
There are a few dead pixels at the very edge of the screen(not sure if that has anything to do it with it or not).
This shows the dim desktop. You can see the light at the edge of the screen.