Bummer,that's really bad luck. If it's epoxy grout you will never be able remove it. That stuff won't even come off smooth tile when allowed to dry. If you used an additive instead of water in grout,most are subseptical to one or more solvents. Determine what the additive is (latex for example) then research for a solvent which will desolve or at least soften it. If you can soften it a hard plastic brush on a drill will remove it. If it's plain non-sanded grout,the brush might remove it after soaking in water. The name "Polyblend" sound's like urethane. If so,look for solvent that desolve's/softens urethane.

you can try Grout Release and see if that works.

also, head over to the John Bridge Tile Forum and read up in the Cleaning forum.

You can try mineral spirits. ( try in one are before going on the rest of the tile & Use rubber gloves)

Thank you for the advice. We ended up waiting a few days to allow the grout to cure and for us to recover and then used sulfamic acid and lots of time and muscle.