Make sure the Amazon network rules allow Echo Requests. 
Go to the Security Group for the EC2.
- right click, select inbound rules
 
- A: select Add Rule
 
- B: Select Custom ICMP Rule - IPv4
 
- C: Select Echo Request
 
- D: Select either Anywhere or My IP
 
- E: Select Save
 
This will help you get access to your instance from outside the network.