While debugging the hang problem I was keenly aware that I could brick my OS.
Well I have done it! I loaded a image of the OS firmware that had a bug
that prevented it from coming up. This prevented using the 192.168.4.1/update
process.
It took me a long time to figure out the flash programming process on the OS.
There is a program capable of communicating with the ESP8266 module using
the ASYNC port available on the 6 pin edge connector on the OS. The
ESP8266 flash write program is called esptool.py. It is available on
github. However, out of a few hundred tries I could only get it to work
3 or 4 times.
The problem turned out to be GPIO 2 (pin 17 on the ESP8266 module) must
be pulled up by a resistor. It is left floating. This pin is connected
to the “B1” button. I put a 10K resistor from the B1 button to the +3.3
supply. Now I can get into boot mode reliably.
I can now download firmware images. I still cannot get the OS firmware
to run even with known good firmware; the latest release os_219_rev7.bin.
There must be something that I am missing. The display does not light
up and the WiFi does not come up.