I buy some nodeMCU on ebay,
i load the last micropython (1.12)... at boot i saw REPL and after 8s the device boot.
I find some info in the forum (here)... I have to run this :

import network; network.WLAN(network.AP_IF).active(False)

and it works very well. All my board could actually work with micropython if i disable wifi AP mode at start.

i try STA mod and it works well but if i try AP mod, the boot loop start again...

So i tried to flash with arduino an AP mode test program and ... It works !

Obviously there is somethings wrong with this board when AP mode start with micropython.
Some people in the forum says that it could be a lack of power and to solve that, put a 100µF cap between NE and ground... i don't try this because it works with arduino without it... That's why i think that it's not an hardware problem.

is someone interested by my problem ?