28Sep/141
avrdude: stk500():not in sync: resp=0x00
The Problem:
Trying to flash the Hobbyking  OrangeRX Open LRS 433MHz Transmitter 1W ( JR Compatible) with openLRS produced the error "avrdude: stk500():not in sync: resp=0x00" in the Arduino IDE.
The solution:
Buy a 3.3V USBAsp board and following the guide here, flash the bootloader to the board. Once the bootloader was installed, the openLRS firmware uploaded without any errors.