We have a project which we have built about half a dozen of in the past, that use the 7" Raspberry Pi touchscreen, a Raspberry Pi 2, and a handful of additional components. The first time we made one of these we saved the SD card drive image as a file and then just used that to flash the drives for all the remaining ones, saving us the setup and installation process. So far it's worked with no problems.
Today I received parts for three more and started building them up. I noticed that unlike the previous touchscreens, these three arrived with the small control board already installed and connected to the two ribbon cables to the screen. Didn't think much of it.
More importantly, none of the three screens seem to work. I flashed the OS onto the SD card, installed it, and connected the Pi to the screen. On applying power the Pi boots up, but the screen stays black. I can attach a HDMI cable and watch the Pi boot up, but nothing seems to make the screen work.
I tried swapping these screens with known good working screens that we had from an earlier production run. The problem seems to be with the screens, not the Pi or the SD card. It doesn't seem to be an issue of updating the drivers or setting configuration options, since the disk image works with the older screens. It appears that we have three dead on arrival screens.
Is there anything else I can try before packing these up and sending them back for a refund?