Hello from Athens Greece.

Tonight i finished building the Picade 10inch with Raspberry PI 3b+.

When i turn it on it always saying that the hdmi has no signal.

What should i do?

Also i tried another HDMI cable but nothing again.

Please help me!!

Try adding hdmi_force_hotplug=1 to your config.txt file.
run the following from command line to edit that file.
sudo nano /boot/config.txt

Thank you very much! It worked!

Now it doesnt recognise my controls.

What should i do?

That I don’t know, I don’t own a Picade, and don’t game on my Pi.

I guess you will have fixed it, but if not, I will tell you that you have to install the X HAT software to make it work properly.

And with which command will i do that?

You have to be connected to the internet.
To run the installer, open a terminal and type:

curl | bash

You’ll need to reboot once the installation is complete, if it doesn’t prompt you to do so.