Hi Marrion,
I'm in the same situation as the Op, old surface died and replaced with a new one but can't get the old pen to pair...
https://support.microsoft.com/en-au/help/4023523/surface-troubleshoot-microsoft-surface-pen
According to this troubleshooting article, if the light only blinks for 2-3 seconds then it's already paired with another device but doesn't mention how to un-pair if we don't have access to the old surface?
Perfectly good pen, definitely not spending another $100 dollars for no reason!
Any help appreciated...
Cheers