Your seedlings seem to be dying from heat stress.
My advice: start over and keep them for the first two weeks (15 days) in a controlled temperature environment around 25 degrees Celsius and humidity of 60 - 80%
You can find simple humidity and temperature meters very cheap online.
They should also have direct sunlight but NOT during the peak hours of the day, or be under a CFL lamp or LED lamp with about 250 PPFD.
Good luck and happy growing!