It started overheating. The fan turns on

Good morning, the problems starts off with the Freeze plugs being cracked. I did what I had to dow hich was remove drain the cooling system and take out the radiator. I replaced the freeze plugs and put everything back together. I bought PEAKS radiator flush system which was a solution that I needed to put int he radiator mixed with water and run the car for 6-8 hours before draining it and adding the antifreeze. The car right now still has the Peak and water mixture and it started overheating. The fan turns on and it has a new thermostat that I put in about two months ago. What can I do?