Brand New Astoria AL steamer spitting water from boiler

[OneZo97]

New to commercial coffee machines. I had purchased an Astoria AL single wand steamer back in March, but I just now installed it (plumbed). Upon turning the machine on and opening the water inlet valve, the boiler fills up but spews water out of this safety valve on top of the boiler. Can anyone point me in the right direction for troubleshooting?

Things to know:

-unit sat in storage for 7 months
-brand new machine