I took a class at Home Depot about laying satillo pavers (the mexican pavers). That is fine and I have been doing great however... I had someone come in to help me with the grouting. This worker spilled grout all over about a 4'X4' area and it dried. It is now seemingly impossible to get up. I have tried a hand sander and phosphoric acid but they barely make a dent. These work where the grout spill is not thick but the places where it is thick remain covered with the hardened grout. How can I get this up or do I need to rip out the section? If I need to rip out the tile what is the best way?