My Jeep won't start or even crank if it's hot outside and the windows are closed.

Sounds like you have a bad ground connection which would actually be under the hood. When it's wet the water becomes the conductor, but when it's hot and everything is dry the corroded bad connection causes your problem. I suggest it's under the hood because there hopefully isn't any water inside of your car to conduct the electricity/ complete the ground.

Hi! I have the same issue, where you able to solve it? how did you solve it? I would really appreciate if you could let me know Thanks in advance