Black screen after kernel loads

Hi, I have a Colibri T20 module with a compiled Yocto Linux with a QT4 application. Everything was working OK (application is starting from a service) but suddenly the display doesn´t show nothing; after kernel loads a black screen appears but, the QT application is running! I now this because if I touch the screen in the app buttons are clicked! (besides an htop to confirm)

(splash screen from kernel is showing ok)

I attached the log but there are a couple of message that seems weird…:

 6.000834] systemd[1]: Cannot add dependency job for unit display-manager.service, ignoring: Unit display-manager.service failed to load: No such file or directory.

Do you have any idea?

Thanks,

Colibri T20 512
Linux colibri-t20 3.1.10-ga699c4f #5 SMP PREEMPT Mon Feb 24 22:31:26 -03 2020 armv7l GNU/Linux

Looks like files or folders related display-manager.service got corrupted or deleted. Could you try re-flash Linux image from scratch?

Yes that works…I don´t have more info; let you know if happen again, thanks!