Why is there a black screen when starting SuperMicro?

Question

Server equipment

There is SupeMicro Model 826-9, SSG-6028R-E1CR12T. I connected everything correctly power, network, VGA, but at startup a couple of seconds of warning that the cable is not connected, what do you think is the problem? The server does not emit signals when starting

Answer 1

Is IPMI working? what does it show?

Answer 2

I believe the monitor was checked and connected to another one.
The other day I had such that the server turned on and worked, I could log in over the network, but there was nothing on the VGA output.
You can try to reset the BIOS, remove / insert memory, turn it on with another power supply if any.
If the server is no longer under warranty, consider a new server or motherboard.