An error happens during coding blinks. I tried plugging in and out, but it didn’t work. I tried restarting arduino, but it didn’t work as well.
avrdude: Version 6.3, compiled on Jan 17 2017 at 12:01:35 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2014 Joerg Wunsch System wide configuration file is "/Applications/Arduino.app/Contents/Java/hardware/tools/avr/etc/avrdude.conf" User configuration file is "/Users/liushiyun/.avrduderc" User configuration file does not exist or is not a regular file, skipping Using Port : usb Using Programmer : usbtiny Setting bit clk period : 3.0 avrdude: Error: Could not find USBtiny device (0x1781/0xc9f) avrdude done. Thank you. the selected serial port does not exist or your board is not connected```