Thanks for your feedback.
My first issue is how to get back control of this PC!
Unable to have a Live usb key start!
No boot with USB key? Which one I have to select?
If I want to add a boot, no choice for USB key!
I think, the trouble is here, with the system update issue!
I reported here: Failed To Update on Zorin OS 17.3 Pro - #10 by Ponce-De-Leon
Thank you for your help.
José