hired a person to apply polyurethane to concrete floors. 1400sq ft. They went around the floor with a floor sander polisher. They did the edges with an orbital sander. Spent an hour. They opened the doors and blew it out with a leaf blower. Then started applying the poly. I arrived about then and started questing it. The poly looks poor. lots of dirt in it as well as roll marks. I tried to dand a section by a door that had a big blob to see if it could be repaired. It dtarted to lift so i grabed a scraper and 1 foot area just peeled up. i went around and tested some other areas. some have good adhesion and some so so. the cement underneath is nice. any tips on how i can get this stuff up without grinding the floor.?