I have a problem, I installed manjaro in ssd and zorin in cpu. My laptop is a Samsung rv 415, amd300 2 Gb of ram. I select manjaro in grub but is not opening only zorin. What I can do with it?

Are you using an Nvidia card?
This may be caused by an incomparability with Manjaro kernel and Nvidia driver. You can try upgrading the kernel or booting to an earlier working kernel in Manjaro with the Advanced grub menu, then upgrading the Nvidia drivers and kernel.

If this is a fresh installation of Manjaro, then you might just reinstall Manjaro itself.