'steamservice.exe' doesn't work and repairing just stalls

I was setting up my Steam install on my computer, and when I went to start Steam it kept bugging me that the Steam Service wasn't working, and it wanted me to set it up again.

When I press 'cancel', Steam starts up. But when I try to start Rebel Galaxy, the game won't start. When I select to set it up again, the dialogue stops responding. Googling the issue I got the suggestion to start the Steam Service repair function through [Steam Directory]\bin\steamservice.exe /repair, but it just sits there doing nothing.

How can I fix this?

My issue occurred because I copied and pasted the entire Steam Library I had thus far. This was around 3TB of data, and when you repair using 'steamservice.exe', it will scan your entire library.

To fix this, I did the following:

1. Rename the 'steamapps' folder to 'steamapps-bak';
2. Run Steam. When it complains about the Steam Service have it repair itself;
3. After Steam boots again, confirm the Service has been fixed by shutting down and starting up Steam again;
4. Shut down Steam;
5. Rename 'steamapps-bak' to 'steamapps'. When prompted, overwrite any file or folder.

Depending on the size, and how long you want to wait, you can just copy your original 'steamapps' folder to another location. However, when I renamed 'steamapps' to 'steamapps-bak' it took no time at all.

Also, depending on your OS, step 5 might fail because of the existing 'steamapps' folder (I use Windows 10 and there was no issue, but I do recall older OS's complaining when you try to rename a folder to one that already exists in the same location).
In this case I would

1. copy anything that's in 'steamapps' into 'steamapps-bak' choosing not to overwrite any file if asked (folders are fine);
2. Delete 'steamapps';
3. Rename 'steamapps-bak' to 'steamapps'.