If a motherboard had just been replaced, and the computer cannot boot up properly, one thing to check is a setting in the BIOS. If the motherboard has been replaced and you receive a blue screen error upon boot up, the issue can simply be a BIOS setting. A computer that is not booting up properly can be caused by many other reason, and the BIOS setting is only one possbility.
To get to the setting, Press F2 to get into the BIOS options menu. Then select “System Configuration” then select “SATA Operation.” In this option, you will see three settings called Disabled, AHCI, and RAID On. Select either AHCI or RAID On depending on which one is causing the computer not to boot properly. For example, if the computer was not booting up properly and the setting was on RAID On, then you would select the other option which would be AHCI. This is only one possible cause that a computer may not boot after a motherboard replacement. These settings would be a good place to start to try and check what is a causing the issue if your computer is not booting properly after a motherboard replacement.