Diagnostics Code -2002D

By "system diagnostics" are you referring to "Apple Diagnostics?" If so "-2002D is not an Apple Diagnostics reference/error code. Something similar to this code would be while using Apple's Internet Recovery Mode and there is something amiss with the Internet connection. Are you sure you got this result after running Apple Diagnostics?

Ref:

• Use Apple Diagnostics to test your Mac - Apple Support
• Apple Diagnostics reference codes - Apple Support

It usually means " -2002D " there is active and functioning internet connection.

For better possible results connect via an Ethernet Cable to Router