I like to do little hearts over places like that.

If necessary you can applique a small piece of the same fabric over the cut so it blends in. Do it like a tiny piece of a "stem" right sides together and stitch as close to the cut as possible. Roll, tuck and stitch down the other side as close to the cut as possible, If you don't want to stitch you can fuse a small piece of matching fabric to the back and a tiny sliver of Misty Fuse to the top instead of Fray Block or in addition to Fray Block. Hope this helps.

I'm try to be careful when I cut but have been known to snip where I shouldn't have. After saying a few not-to-be-said-in-front-of-children words, I try to recut the piece. I usually over-estimate my fabric needs (there's always something I can do with extra fabric) but these suggestions are great. I'll be adding them to my tips/hints/suggestion folder.

you said alphabet blocks could you applique a figure with the name of something that starts with that letter over the cuts

if pattern appropriate, I use yos yos over the area......

Embroidery thread is your friend! I've accidentally snipped a top when quilting. I use the same color embroidery thread (or a contrast if it fits) to whip stitch the small cut together then cover with a heart in satin stitch. Works beautifully and launders well.

I call it a bit of hidden love! Folks are tickled when they find them. Little do they know, that heart is hiding an oopsie!

Add fusible under the block to hold the cuts shut. Then either applique or decorative stitch with machine over. If you go the machine stitch route, you will also need a stabilizer under it. Good luck.

This is exactly what I had to do in my earlier days of rotary cutting. I was not concerned with being able to feel the fray check and Steam-A-Seam later on since they were such small mistakes. Also, quilting over them helps stabilize the fabric around the cuts and distributes the pull, wear and tear of the quilt. No worries!

well since they are ABC blocks from a kit \, I would first put seam to seam on black and then use some kind of applique
over each block so they look like it was what you wanted to do....................But there is always a way to fix small mistakes..........so sorry it happen to you.
I know how bad u felt Been there done that

I would applique something over the cuts.