Every AMD CPU is tested just before it is boxed and it's almost impossible to damage them in transit because of the specially designed package. Mobos are rarely bad also but Asus does use multiple manufacturers for their mobos so anything is possible.
The most common fail to boot issue on new PC builds IME is connecting all of the 12V power feeds required for the mobo and GPU cards. These days both the mobos and GPU cards often require 2 or more independnet 12V power cables to be connected in addition to the main 24 pin connector.
Depending on your time factor you might be able to find someone locally who either has a mobo that your new CPU will fit into or someone who has a CPU that will fit into your mobo. There are also online tutorials for "bread board testing" just in case there is some grounding out issue with the new mobo in you PC case. Bread boarding eliminates a lot of potential issues and is a pretty quick check to see if the hardware is working OK before installing in the case.
Building a reliable PC involves more than just assembling the parts. You need to be able to configure all of the BIOS settings appropriately. This can be quite involved and frustrating as it can require a lot of trial and error with stress testing. It is however often the only means to get a 100% reliable PC.