Thank you so much for sharing this, I had some trouble with the block, too! I was making a baby blanket, and on the second block I sewed a square wrong side up. It would have meant tearing the whole thing apart...I was so frustrated I trashed it, used the one block that worked as a centerpiece, and cut up the rest of the fabric and used around it.
I'll probably try it again, but in no way was this 10-minute block foolproof!
Laurie