An "upgrade to 12.5.2 on a new machine"? That's technically not an upgrade, it's a new install. Unless you have unallocated licenses left in your SAP account, you'd need to follow Terry's advice and check the old license in first. That should free up one, and you can regenerate it for the new machine.
It failed because you were trying to apply the license for the old machine on the new one, and SySAM worked perfectly to prevent that. That's the exact situation it was created for.