Question Boot LED won't go off ?

[PixiePetal]

I just upgraded my motherboard (and had to upgrade my processor too, love that) and while ive had many issues getting it to work, this is stumping me the hardest.
I can only boot up into bios, and the boot led is active. Ive been told its because it can't find my OS, but the problem is that my computer SEES my hard drive, listed under my SATA ports, but it won't let me put it in boot priority. Any ideas why?
Specs:

Msi z490 gaming edge wifi
Intel i7 10th gen processor
GEforce gtx 1060
2 sticks ddr4 ram
Wdc Wd5000acs harddrive
Cx65om corsair power supply
Samsung ssd pm

 

[rgd1101]

What was the old system?
What the os?