Tablets freezed

We are experiencing this problem with some tablets. Here is a video that shows the symptoms:

The tablets are brand new devices with these characteristics : 4GB ram , 64GB storage, CPU Octa core MediaTek, display 8", 5100mah battery.

What is the recommended troubleshooting for this issue?

General recommendations:

Update tablet to the latest firmware.
If you see degrading of performance of the Interviewer app - restart the app.
If you see degrading of performance of the tablet in general - restart the tablet.

We do not have reported issues like that. There could be different reasons including an issue with devices.
Do you have any information prior the occurrence?
Something like this: 5 interviews were answered and in particular section or on answering to some question it happened.