Huawei e5573cs-322 Quick Start Manual page 13

Charge your Mobile WiFi for a while and power it back on.
Why did my Mobile WiFi power off all of a sudden?
Your Mobile WiFi may overheat when you use it continuously over a
long period of time, and thereby trigger its automated protection
system. Wi-Fi will be turned off and your Mobile WiFi will power off if
this occurs.
Please ensure the device is properly ventilated and cooled before you
power it on again.
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