reproduce:
minicom (see how to configure for desired tty) try minicom -s
now abruptly disconnect in minicom; this is hit (to show menu) esc Z, hit Quit with no reset.Q
reconnect, serial communication is now open but there is no response from device. No command are operational. Example v doesn't respond anything.
-> solution for now, unplug/replug device.
Interesting, the same works nice for l mode.