Why does the CL28R downshift to a lower mode after being used for a while and the higher mode cannot be selected?Updated a year ago

The reasons are: 

1. Intelligent Overheat Protection 

The lantern will accumulate a lot of heat when used on Med or High modes for extended periods. When the lantern reaches a temperature of 54°C or above, the lantern will automatically decrease a few lumens every 1 second to reduce the temperature.  When  the  temperature  drops  below  54°C,  the  lantern  will automatically increase a few lumens every 1 second, it will then allow the user the reselection of Med or High modes. 

2. Low-voltage Warning

When the voltage level drops below the preset level, the battery level indicator constantly blinks to remind you to timely recharge the battery. To ensure normal use, the lantern will not turn off automatically and will work till the battery level runs out