iPhone SE both cameras not working after screen repair

I recently replaced the screen on my iPhone SE. After the repair, I found that the front and rear cameras both no longer work; the camera app simply displays a black screen and other applications like Snapchat say that they cannot access the camera. The flash also doesn’t work, but the proximity sensor, earpiece, and auto display brightness feature are all working fine. I’m on the latest version of iOS, and I reopened the phone to check that all ribbon cables are plugged in properly. Any ideas?