White Q-LED (3rd of the four Q-LEDs) means: A graphics card is missing or something is wrong with it. The Ryzen doesn´t provide an integrated graphics unit, so the motherboard´s connections are not enabled/usable. You will need to get a graphics card or an APU processor with integrated graphics unit.
Other than that the code 50 says that the memory is not correctly installed or incompatible. Where did you plug in the RAM? Recommended slots from ASUS would be slot A2 and B2 (for dual channel, if you are using 2 sticks). That´s from the CPU the 2nd and the 4th slot.
Updating the BIOS could help there too, via the flashback feature of your motherboard:
https://www.asus.com/us/support/FAQ/1030111
https://www.asus.com/us/Motherboards/ROG-CROSSHAIR-VII-HERO/HelpDesk_BIOS/