Question New PC beeping after not being used for 1 day

[route45]

I have a new PC (1 week old) that I didn't get to use yesterday.

Today, as I turn it on, it does repeated beeps (dot dot dot dot pause dot) and I've been trying out the pattern but couldn't determine much.

Mobo: MSI H510M Pro-E
RAM: 2x TForce 8GB
GPU: GeForce RTX 3050 Zotac
CPU: i5 10400F

Update: Tried to run Windows Diagnostic Memory, it wasn't the RAM
Another update: My HDD is suddenly not appearing

 

[Lutfij]

You forgot to mention the make and model of your PSU. If you're able to get into BIOS, can you check and see what your current BIOS version is?