Can you please recheck the JRE that is configured with TomEE 1.7? TomEE 1.7 is not compatible with Java version greater than 8.
Double click on the server in the Servers view to open the Overview page. Click on ‘Runtime Environment’ and set the JRE to 1.8 or lower. Apply the changes and you should now be able to start the server successfully.
If you are still seeing issues, then please share the MyEclipse version details from Help > About MyEclipse dialog, the exact version of JRE that is configured with TomEE 1.7 and also share with us the entire contents of the Console view to help us get full failure details.