make sure the MBL is connected by cable to the router. Turn off the MBL. Turn off the router. Turn on the router. Wait a minute. Turn on the MBL. Wait 5 minutes. Look in router web-interface for the assigned IP address of the MBL.
in your web browser, type the IP address of the MBL.
That’s an easy fix. Just use one of the Debrick Guides from this forum. Particularly one which erases all the data. You are not the first to install the OS on a new disk.
try the debrick again. You might have done something wrong. Also using your linux pc, look at the disk to make sure that you actually installed the OS on the new disk.
Also make sure that your router is ok. And then look for the MBL IP address in the router’s interface.