dsvilko wrote: It just won't boot from the spi flash.
So what exactly happened when you connected to it with your serial terminal software?
Which terminal software did you use?
What baud rate?
Sorry if you've been through this already but the thread above is muddled with several different scenarios.
I don't use Nodemcu but I think the eventual output is something like this:
NodeMCU 0.9.5 build 20150107 powered by Lua 5.1.4