Before the SSD got added... was the HDD your boot drive? If the answer is yes, my guess would be that the shop that did the SSD install didn't touch the HDD and it would still be bootable.
Try to boot from the HDD inside of your Mac. Shut down your machine. Turn it back on and at the same time hold down the option key and keep it down until the boot selection menu appears. If you see your Media HHD, select it as your boot drive and away you go. Then you could use it to check and repair the SSD if it is needed using the Disk Utility app.
Your SSD is new and the firmware that it shipped with is not old. It should work just fine with your Mac.
You could have a faulty SSD or more likely when the machine was re-assembled after the SSD install a cable was not properly seated and it making poor contact.
I already wiped my 'Media HDD' so it is no longer bootable.
As far as the firmware goes, it IS outdated, by 1 version. They released a new update just days after I ordered mine. I'm trying to get that updated but not sure how.
I don't think it would be an installation / connectivity problem because I think I would have a lot more problems than just freezing after waking from sleep.
My Mac didn't freeze at all yesterday.... but I'll test again when I get home (it's been sleeping all night and all day)
I'm downloading the .iso to my work PC and going to try to create a bootable flash again this way if possible.