Global Telecom MiFi Hotspot screen goes blank/powers off.
Ensure the Hotspot is not just going into sleep mode. If you are able to tap down the power button and it turns back on, it is just a sleep mode.
Otherwise, you may have a defective Hotspot/bad battery and will need to be replaced.
The Hotspot has a sleep mode that conserves the screen and battery, everything will work while the screen is off.
Otherwise, normal wear and use can cause the battery and Hotspot to no longer function.