You should at least see an error message on the serial console. Those error messages can help debug the system.
If you have never booted anything other than the original freedom-u-sdk image, then the most likely problem is that the MSEL switches are in the wrong position.
The fedora instructions don’t mention the MSEL switch settings. See the picture at
and make sure your switches are in the same position. Ignore all of the other stuff about openembedded. It is just the MSEL switches that are probably in the wrong position. The original freedom-u-sdk image requires all of the switches down, but anything newer using u-boot requires the settings shown in that picture in the running on hardware section.
If that doesn’t work, then you should try verifying your SDcard, and make sure the image on it is OK.