Restore Deleted Site Collection

Question

I'm trying to restore a site collection that has somehow been marked 'Deleted'. I've been unable to restore it, as we're unable to reference it with any of the following options:

• Restore-SPDeletedSite <GUID>
• Get-SPDeletedSite <GUID>, just running Get-SPDeletedSite returns null
• Checking for it in the Central Admin recycle bin (unsure if this would work)
• Dismounting and re-mounting the content database
• Creating a new Site Collection with a subsite, and remounting the old content database

The last option ended up creating a new site collection in our old content database that's just an empty site collection. Our other sites are still accessible (eg .../sites/Archive), but the root site collection and its subsites are inaccessible.

We know it's been deleted in some fashion because after going to the SQL server and running a query on the Site Collection in question. The query was:

SELECT [Id],[Deleted]  FROM [Content_Intranet_DB].[dbo].[AllSites] 
WHERE ID='DD1CC06F-8BCC-4A0E-B8D1-96A25047BFB4'

Which returned the following results.

Is there any way to make the root site collection re-accessible/undeleted except for the above attempts?

We don't have a backup of this, as it's a UAT/testing environment but there was some people doing development work on it before it disappeared. It looks like all of the content is still present (the database is the same size as before, the site looks like it's just a toggled deleted flag, etc).