I've got two ESP12 today and was facing the same problems, but i think i figured out how to solve them
First, connect the GPIOs like following and then reset the unit, using the reset pin:
GPIO0 -> LOW
GPIO2 -> HIGH
GPIO15 -> LOW
You should be in serial Flashmode now! I used the NodeMCU Flash tool with 57600 baud to flashNodeMCU 0.9.5 build 20150214. After successful flashing, connect the GPIOs like following an reset again:
GPIO0 -> HIGH (or even not connected!)
GPIO2 -> HIGH
GPIO15 -> LOW
Now you should be able to connect over serial line at 9600baud
I successfully tried this method on two esp12.
Best Regards from Euskirchen, Germany
Martin
http://www.conzi.com
I thought CH340 boards were better than that.