I don't know why Fix Broken Links didn't work. The other option is Search>Search and Replace>Multimedia File names. If you use it, you won't actually be changing any file names. Rather, you will be changing file paths.
You can look in RM's media gallery to see the file path for any file as it was on your old machine. You should be able to figure out the file paths of where your files are on the new machine.
For example, here is a rather longish file path from RM on my system.
C:\Users\jbryan\Dropbox\mybackup\aalevel2\mywebpages\rm_media\birth_folder\peters_arthur_birth_index_page35a.png
The "jbryan" is my Windows userid on my machine. If I went to a new machine where my Windows userid was "jerry", I might user RM's search and replace to change C:\Users\jbryan to C:\Users\jerry The file path would then become
C:\Users\jerry\Dropbox\mybackup\aalevel2\mywebpages\rm_media\birth_folder\peters_arthur_birth_index_page35a.png
By the way and not to overload you with too much information, the way RM keeps track of media files is called an absolute file path. For users with more than one machine in their home, it can make using RM on more than one of the machines (and not at the same time!!) awkward unless the location of the RM's media files is exactly the same on both machines. Therefore, another solution to your problem might be to set up your file path on your new machine exactly the same way it was on your old machine. If you did it that way and put your files there on your new machine, the red X's would vanish instantly with no further effort on your part. Basically, you start out with C:\Users\usersname (where "username" is the Windows userid which has to be the same on both machines). Then, the rest of the structure has to be the same. As you can see, I use Dropbox rather than OneDrive, but the two products operate in a very similar manner. But If I weren't running Dropbox or OneDrive, then I would put my RM media folder under My Documents. Quite a few users also have a separate hard disk (not removable) for their data so you will see things like their data being on D:\ rather than on C:\.
In any case, if you can get the file structure the same on both machines and put the RM media in the same place on both machines, then the red X's should vanish. If you can get RM's Search and Replace to work, the red X's should vanish. If you can get Fix Broken Links to work, the red X's should vanish.I'm extremely puzzled as to why Fix Broken Links didn't work. It's like you files really aren't on your new laptop yet.
Jerry