This usually happens when the Eli App cannot use your camera. Turn on camera access to fix it.
For iPhone
1. Open the Settings app.
2. Tap Privacy & Security.
3. Tap Camera.
4. Find the Eli App in the list.
5. Turn on the switch next to the Eli App.
6. Open the Eli App and scan the test again.
Apple's guide on how to change permissions is here
For Android
1. Open the Settings app.
2. Tap Apps.
3. Tap the Eli App. If you cannot find it, tap See all apps first.
4. Tap Permissions.
5. Tap Camera.
6. Tap Allow.
7. Open the Eli App and scan the test again.
Apple's guide on how to change permissions is here
Still a black screen? Close the Eli App fully and open it again.
If that still doesn't work, then contact our Support team.