I have a 2005 ford explorer and it start in the morning when I go to work but in afternoon no starting?

I have a 2005 ford explorer and when go to work it starts fine but when it sits in the sun when it's time for me to get off no start the radio turns on like everything else but no start also my theft system flashes really fast when I turn the key to try and start it but nothing I have used my other transponder key but still the same thing I just had a new starter put in and I really don't know the issue please I need answers bad somebody…

Before you do anything more expensive try removing, cleaning and reinstalling all the electrical connections between the battery and the starter on the positive cable. Then do the same on the negative cable at the battery post and the other end where it attaches to the engine block. Your symptoms can often be caused by corroded connections, its a cheap fix and doesn't take long to do.