CH340 Nano avrdude: stk500_getsync() not in sync resp=0xa4
Arduino has recently changed to using a different bootloader on their official Nano boards that communicates at 115200 baud rather than the previous 57600 baud. Support for these new boards was added in Arduino AVR Boards 1.6.21. The new Nano board definition is not compatible with old Nanos and likely most 3rd party Nanos so backwards compatibility is provided via the Tools > Processor > ATmega328P (Old Bootloader) menu selection.