WHEW....I've never heard of that kind of a failure being an accident, that it. If your back up was SSD also, then I'd suspect there was an external event, like a power pulse (lighting discharge?). I can't imagine how that would happen if your back up was a mechanical HD....unless it was a worm with a timed destruct.
Best of luck with the recovery, but don't hold much hope. I had similar problems with a main HD failure and even paid some Pros to try and recover the data...to no luck.
Sorry to hear of your disaster.
A lot of it I can rebuild, but there are certain things I'll be unable to recover... I had done a ton of artwork and stories for various games, written 300 pages of a story for my LotRO character, written around 20 pages of my Thesis, plus had copies of all the articles I'd downloaded (I'd have to redo the 7 years or so of research to find them all again). There's websites I used to visit a lot, the addresses of which I can't remember, and so I can't even FIND now. There's a HOST of pictures I can't replace, like the last visit of my aunt and uncle from Scotland, who are dead now. Videos, music, movies... All gone. It's eating my brain, let me tell you.
That everything would die at the same time... it's SO unlikely. And it's the SECOND TIME this kind of thing has happened. Last time, I went out and bought a new PC. I moved all my stuff onto a USB stick to transfer to the new PC, then got rid of the old one. AS I was transferring all my stuff to the new PC, the USB stick quit working. Unrecoverable.
I swear, with the odds I keep beating, I need to go buy a lottery ticket, but I'm afraid with my luck I'd end up owing THEM money.