I'm facing the same problem of no REPL after have compiled the firmware ( see post viewtopic.php?f=16&t=5490
In my case the issue is present also if I compile the firmware w/o add any frozen module.
PYB: soft reboot
Activated UART(0) for REPL
MicroPython v1.9.4-683-gd94aa57 on 2018-11-05; ESP module with ESP8266
Type "help()" for more information.
This is the boot.py :
# This file is executed on every boot (including wake-boot from deepsleep)
and this is the content of the two directory where the firmware modules are stored :
During the compilation of firmware I don't have any error so I've not idea at all wher could be the issue.