There are such low reviews of the two main kinds of concrete resurfacers: Quikrete and Sakrete that I don't know what to do. Any ideas on recommendations on a concrete resurfacer for a driveway in California?

hi gang. so here is the deal. I hired a guy to help level my concrete patio. water was pooling, he was going to get the slope better so it ran off the side into a new drain in the low spots. before doing another skim-layer topcoat all over. he tried a couple different brand of self leveler but either didn't mix it right, work fast enough, was too hot out or how didn't know what he was doing. so I come back from my short trip and the work isn't done, he cant be found and there is a 5 foot by 7 foot area where it looks like he tried make it work but quit. so assuming I cannot find him, what do you recommend? will I have to just chisel this off? is there a grinder wheel attachment or anything I can get for my angle grinder or drill? A buddy said they rent commercial concrete grinders at Sunbelt (about $75/day) but they chew through wheels quickly supposedy. Or is there a chemical solution? gotta get this cleaned up as now it looks worse than before he began. photo attached. as always, thanks!