It looks like a poweroff signal is sent through CEC, or directly to Vero (does it have an IR receiver built in?). This happens when I press the power button on my TV remote.
In /usr/share/kodi/system/keymaps/remote.xml, this line is set:
<power>ShutDown()</power>
After removing that line, upon pressing the power button on my remote, the Vero doesn’t turn off anymore.