The original Alloy Start menu button won't match these black taskbars.
Better to download an Alien orb 7 type start button from internet.

Downloaded example from SimplexDesignsArt:

https://simplexdesignsart.deviantart.com/art/Alienware-One-Start-Button-167443301



Here a few more links:

https://www.deviantart.com/art/Alienware-Blue-Start-Orb-205113836

https://www.deviantart.com/art/Alienware-Start-ORB-186958755

https://theend1984.deviantart.com/art/Alienware-Steel-Start-Orb-v2-167202488

https://romanbob2004.deviantart.com/art/Alien-start-buttons-166796505

https://www.deviantart.com/art/Mega-Orb-Pack-150-start-orbs-259940654