-501 0D

A old Macbook running OS Sierra does not start.

I run the short Hardware Test, which came out fine.

I ran the long Hardware Test, which froze after 2hr 37 minutes, unresponsive.

I restarted the computer into Hardware test again. Shortly after I had entered the Network password, the computer froze, showing a globe with an exclamation mark over it, and underneath the words "apple.com/support" and under that the line "-501 0D"

Does anybody have any idea what this means?