Temps are not the issue, but giving them any type of fertilizer/stimulant at this young age is the problem and the cause of the issues, as well as being too dry.
Plain water for the first 2 weeks is best.
As long as you keep the soil moist, temps and direct sun light will not harm them, they have been growing like that since forever.
I grow outdoors in the open for over 35 years now and my seedlings do not suffer in direct sun, even 2 days old and so long as they are ever kept correctly hydrated, even if this means watering twice a day.
In high temps you will need to water deeply and to run off, not just little amounts.
To rescue them, keep them moist and in part shade, avoiding the sun at the hottest part of the day, say 11am until 3pm and they should recover soon enough, but remember, plain water for baby seedlings only.
Hope this helps, Organoman.