Can you break an iPad by keeping it in a warm place?
You didn't say if you had let the iPad cool down, but the inside of a sealed car on a hot sunny day can go over 125°F. 

If it has cooled down and still does not work, perhaps it has been baked to death. You might want to take it to an Apple Store, if convenient.

From Apple Support:

Environmental Requirements:


Operating ambient temperature: 32° to 95° F (0° to 35° C)
Nonoperating temperature: -4° to 113° F (-20° to 45° C)
Relative humidity: 5% to 95% noncondensing
Maximum operating altitude: 10,000 feet (3000 m)