PC Freezes While Booting Windows or Starting Automatic Repair

I built this custom PC in early 2021, and it has worked normally until now. Windows freezes on the spinning loading dots, and it also hangs at "Preparing Automatic Repair." When it locks up, the keyboard lights turn off as well. I've reset the CMOS, reseated the RAM and NVMe drive, and created a Windows installation USB with Microsoft's Media Creation Tool, but the system still freezes shortly after the BIOS screen—even when trying to boot from USB. The BIOS appears to detect the main hardware. I'm testing the NVMe drive with an enclosure, but I'm wondering what else could cause the system to freeze before Windows or the recovery environment loads.