ESP8266 Community Forum

I am experimenting on an IOT project, using an ESP-12 test board (aliexpress)
After deciding to use nodemcu/lua, I sucessfully flashed the board using ESP8266Flasher, using the built-in version "INTERNAL://NODEMCU"
Then I successfully carried out some experiments using lualoader, and code written with Luaedit2010 including various fragments from the web. Mostly great!
But as I could not get Gmail working I decided to build a new firmware (with SSL) and flash - using nodemcu-build.com
After this flash, i could not get any reply from the board though lualoader, or putty.
So I tried to reflash with the original version "INTERNAL://NODEMCU" -- board still unresponsive.
The flash seems to run, in terms of time taken and appropriate LED's blinking. The only difference I notice is that there is a bit more LED flashing when I reset the board, compared to before.
Any hints where to start? I think I have the basics right (resistors GPIO15 to GND, CH_PD to VCC, and the "flash" jumper is built onto the board, and it all worked once) but am concerned that there is some extra step needed.
Do old FW versions need to be erased?
Is there any extra step needed with lualoader?

just adding to this...
A different flash tool: ESP8266 Flash Downloader can make contact with the ESP, and flash new firmware.
The standard AT set.
Then I can use the NodeMCU flasher again...with the original version "INTERNAL://NODEMCU" and all works.
But if I try and flash in the custom firmware - it is bricked again.
Is this a common experience with custom firmware?