Downloaded esptool, connected GPIO2 to 3.3V and GPIO0 to ground, booted up and executed the esptool as follows (with resulting output).
$ sudo esptool.py --port /dev/tty.usbmodem1451 write_flash 0x000000 Firmware.bin
Connecting...
Traceback (most recent call last):
File "/usr/local/bin/esptool.py", line 5, in <module>
pkg_resources.run_script('esptool==0.1.0', 'esptool.py')
File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 492, in run_script
self.require(requires)[0].run_script(script_name, ns)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 1357, in run_script
exec_(script_code, namespace, namespace)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/pkg_resources.py", line 47, in exec_
exec("""exec code in globs, locs""")
File "<string>", line 1, in <module>
File "/Library/Python/2.7/site-packages/esptool-0.1.0-py2.7.egg/EGG-INFO/scripts/esptool.py", line 471, in <module>
File "/Library/Python/2.7/site-packages/esptool-0.1.0-py2.7.egg/EGG-INFO/scripts/esptool.py", line 149, in connect
Exception: Failed to connect
Have this on two Macs ... What am I overlooking?