What happened:: I sent him code for 100€ Amazon.de Gift Card,after 1min he reedemed the code
That basically marks the end of the trade from his side.It would be stupid of him to not block you since he knew he wasn't going to pay you any bitcoins either way.
What you should do : Try contacting Amazon customer support and let them know what happened of course don't mention bitcoins or a trade was involved.
Lol. This seems like two scammers seeing who's going to lose first. I don't trust folks here who sell gift cards, but maybe this one here was just surplus for OP. But as Lauda has said, you're new, but you really ought to keep your wits about you on this forum and that should be obvious. Better luck next time.