I bought a carbon roof, overall condition is okay, just some minor set back that is not noticeable in a few feet. Up close you can see 1 large crack on the side, and small ones all the around the roof. My problem is the long crack, it seems like it has gone through all the way down to the carbon itself. Is there a way to fill the crack? Do you just sand it and hope the clear coat can get through or do I need resin? How do you spray the clear? Do you sand first, then buff, then respray the clear? Here are some pics

LONG CRACK

Here's a sample of the crack that goes around the roof. Seems like these are sandable then buffable

Here's a big crack but I believe weather trim will cover this part but might as well fix it.

Can you send it back for replacement? I don't think those cracks are going to be simple/easy to fix.

Along those same lines.... I assume this is a used part? Big question for me would be is this "real" carbon fiber? It has an odd look to it, but it could just be the pics. Essentially, you have to treat this stuff much the same way you do fiberglas when it comes to cracking. The cracks have to be opened up in a V shape down as far as they extend (Dremel tooling) then, a water clear epoxy resin must be used to repair the area. Problem is, most often you will still "see" a distortion in the clear when this is done.
When new, the usual drill for carbon fiber pieces is to prep. them for application of an extremely strong UV resistant clear, then do a regular cut and buff.

Yes this is a used part and yes it is real carbon fiber hehe. Opening a V meaning I have to dremel along the cracks? Can I just fill it epoxy resin or fiberglass resin without cutting it? I don't want to ruin the carbon underneath

You could try it but they will certainly come back, how long, hard to tell. The reason you V open a crack like that is to get to the source of where the crack begins and to also increase the amount of surface profile that will hold it together to prevent further cracking. If you just try to "surface soak" the resin you will not get down to the problem and there will be very little surface area to stiffen the structure. The movement that is causing the cracks is starting at the flex in the carbon fiber, that's why you have to get down to it.