I received my Spark 4 today.
Was powering it over USB and having it connected over Ethernet.
The system was disconnecting from the Ethernet quite often and suddenly was completly shut down (dead).
Now it does not beep when it is powered and the display keeps being black.
What I recognized as well before the system went black is that the two delivered ds18b20 had 7 degrees temperature difference.
Power cable is working well an an raspberry4.