My laptop not booting on continuous spinning dots stage

For the last few days Asus ZenBook laptops that hang at the Windows 10 logo with a “spinning dots” for a few minutes, then reboot. It does not go into Startup Repair even if I force it to power off at boot four times in a row.

Even I tried a spare SSD and replacing RAM on the laptop. But still, I am able to boot to Windows 10 DVD even after disabling Secure Boot in BIOS and trying every combination of Legacy/UEFI.

I created a Windows 10 bootable USB drive but wasn’t able to find or correct any issues. Run some startup repair, PC Diagnostics. But sometimes during restart, I can get into BIOS or alternate boot menu.

Extended hardware diagnostics show no hardware errors. All I’ve got left if bad motherboard but the symptoms are strange enough I thought it was worth throwing up here.

Thanks in advance for any ideas!