Plenty Used Wyse Thin Client Model No: TX0, Product ID : T00X 1GR DVI ES INTL

I bought some used Wyse Thin Client Model No: TX0, Product ID : T00X 1GR DVI ES INTL

When powered on, they displayed on monitor but on Citrix receiver's User and Password which I do not have.

Do I need to re-image them outrightly with a new thin OS or ThinLinux ? Or is there a way of having access to Bios for any kind of resetting/re-imaging?