Silvercrest SURB 520 A1 - Manual (Page 25)

Power Bank SUPB 520 A1
24 - English
 No USB connection to power source: check the USB connection .
 The Power Bank battery is missing: insert the battery.
The 20%, 60% and 100%
LEDs are flashing  The Power Bank battery is empty: recharge the battery.
The 60% LED is flashing  The connected device/USB cable is defective: check the connected
USB device.