More generally, given the impressive number of ethernet ports available (2), if ether1 doesn't work, try ether2 ( it may be worse, think of a 48 ports switch 
).
Anyway, if you have a PC running Windows, get Winbox 3.42 from here:
https://mikrotik.com/download
install it, verify that you can access the router (of course you need to have the login credentials, user and password, that I hope the previous owner gave you).
If you have a Linux or Mac, you will have to use the corresponding 4.0 beta 30 version.
Then follow the instructions here:
to get the current configuration and post it on the forum (anonymized).