I have an acquaintance with that same motherboard model (MSI PRO Z790-A WIFI) as your prefab. In his case a long beep that doesn't stop meant a problem with RAM.
Have you already tried removing one stick of RAM at a time? By that I mean remove one RAM stick, launch the game, see if it beeps; if it still beeps, put that RAM stick back on, remove another, launch the game; if you have more than 2 RAM sticks continue until you've tested them all. You might have 1 (or more) faulty RAM sticks.