Selecting Home Network during setup just means that other PCs on your home network will be able to see the drive. The alternative at that point in setup, which is telling the MPW it is connecting to a Hotspot, just means that other PCs and devices on the hotspot network can not see your MPW.
When you connect the MPW to your home WiFi network it will always be hidden behind your router, whether you select Home Network or Hotspot in settings. However at the same time its own WiFi network is always available for devices to connect to, if the MPW WiFi adapter is turned on (as indicated by the blue WiFi LED), which it is when you are connected to your home WiFI network. For example, my MPW is often connected to my home WiFi network, but then I often connect my iPhone directly to the MPW’s WiFi network, like this;
iPhone → MPW → My home WiFi network.
But just because the MPW’s WiFi network is available to connect to, doesn’t mean that it will be visible for others to connect to, as the MPW doesn’t advertise itself unless you press the WPS button and the blue WiFi LED is flashing.
That naming, Home Network and Hotspot, have been replaced in the latest firmware with a check box labelled “Share content on this network” to make understanding easier. You check it when connecting the MPW to your home network, and uncheck it for public networks.
If you did not set a WiFi password for the MPW’s network, how did you set it up? When you first set up the MPW, you must connect to its WiFi network, and when you do you are forced to set a WiFi password. The MPW then reboots and asks you to log into its WiFi network using the password just created, at which time you are then able to set the MPW to connect to your home WiFi network.
You may not remember setting a password for the MPW’s WiFi (MY PASSPORT) network, if it was some time ago, but you did.
It is a pity that your MPW no longer works, because if it did you would easily be able to test this by trying to connect to the MY PASSPORT network from a device, perhaps a smartphone, that has never connected to it before, and therefore hasn’t stored the password. You would be prompted to provide credentials to connect, in the form of a password.