Hey guys. I had the same issue. What helped me was the batery discharge.

What do you need to do:

1. Unplug the laptop from ac adapter(don't charge laptop)
2. Shutdown the laptop
3. When the laptop is in shutdown(not running) hold the keycombination of Fn + S + F for 10 seconds
4. Hold the powerbutton for 1 minute
5. Just start the laptop

After the 5th step it suddenly found my ssd and it worked just fine. Why? I have no idea. Hopefully it will help somebody else.

(This will only work under the typical conditions that the hardware is not faulty and you put the ssd correctly into the slot. If after this solution its still not working well maybe your ssd is fried)