First, I do not think you can give Osmocote the credit for your azalea coming back or give the product blame for the brown on the new blooms. A slow release plant food like Osmocote will usually not "burn" the plant even if you use too much and water well. Could a hot day or too much rain of hit the azaleas that same week? You did the right thing to remove the visible Osmocote but do not continue to flood the soil. Moisture and warm soil is what causes the product to release the fertilizer. I suggest you simply trim back your azaleas now to remove the brown on the tips and blossoms. Keep the soil moist around azaleas during droughts but no more plant food this year.  Pruning always stimulates growth so after you trim your brown azaleas and the old blooms are gone you will see fresh new growth and they will look great. Keep growing, Marianne Binetti