Change licence from old to new computer

Recently I Had to Change the mainboard of my computer. Now I can’t start Rhino because my key only works on the old mainboard.
Ist there any possibility to Change it? How does it work?
I only find teh Option to Change it directly in Rhino. That doesn’t work, because I cannot open it without the key…

I see you have been trying to add the license to your login account.
That won’t be possible until you get Rhino running stand-alone.

When Rhino V6 asks for a license, choose the option to enter your license key “single computer”.

If you want to switch to using a login account instead, after you are running stand alone, then use these instructions to remove the stand-alone license, then you can add it to your login account.
https://wiki.mcneel.com/rhino/6/license

Thank you for your answer.
The Problem is that I can’t start the program to go to Options.

So this solution doesn’t work.

A - To Remove a Single-Computer License

  1. Connect your computer to the Internet

  2. Start Rhino 6

  3. Windows: From the Tools menu, click Options

  4. Mac: From the Rhinoceros menu, click Preferences

  5. Select the Licenses tab (Win) or tool (Mac)

  6. Click Change your license key

  7. Click Remove License

Have you any other idea?

Hello - where does this fail? What happens, anything?

-Pascal