Lets try to get back to the basics and see if we can figure what is going on here. First I would turn off one of the heat lamps. Sounds too hot. Do you have a thermometer in the cage on the floor? The temp a few inches away from the main beam of the bulb should be 85-90 degrees. They should be able to go closer to the light to warm up AND have the option to get away from the light to cool off. Make sure the food and water is in the mid range temp area part of the cage. They will not eat if too hot.
They are too old for sugar water. That should only be used one when they arrive in the mail. Give them only fresh water and medicated chick starter. Electrolytes and vitamins are not needed. 99 in the brooder is too high.
Are they eating and drinking? What do their poops look like?
Please post answers and we'll get you back on the right track.