There are two ways to accomplish this.
1: Scan the special barcode below:
2: Press the scan button combination within 3 seconds (to toggle between modes):
• 3 x Left Scan Button •3 x Right Scan Button •1 x Left Scan Button •1 x Right Scan Button
So, in other words, L-L-L-R-R-R-L-R in 3 seconds. Then you will hear one beep or two beeps confirmation beeps. One beep indicates USB HID mode and two beeps indicates USB Serial.