External SSD with OS installed not working?

Four months ago I bought an external SATA case with USB-C compatibility so I can install my iMac OS there, did this because my iMac has built in HDD and was so slowww..

With the case I started using an ADATA 120GB SSD and everything worked like a charm for the past months, up to now...

As an extra fact I have to say 1 day ago I took the computer to another location (car trip) used like 12 hours and take it back to my office (of course I unplugged the SSD and plugged it back a couple of times), this was the first time EVER I unplugged the SSD case.

Today I was working as usual and the computer suddenly turned off and showed a message like this:

So waited for the iMac to restart and continue working, the message appeared 3 times after 20 minutes aprox of working.

The fourth time the message appeared I tried to start up again and the OS didnt started. The apple logo appears up to the loading bar but it turns off at 30% more or less.

This apple logo thing only happens when starting up from the external SSD, if I boot up from the default HDD it works good (I didnt remove the OS from there cause I knew something like this could happen).

So I would like to know what do you thing could go wrong? Maybe the USB-C cable got damaged in the trip yesterday, or its just that the VANTEC case is not supporting this kind of usage, or even the SSD?

I cant use the iMac with the OS running at the HDD, I've get used to SSD speeds both in my iMac and macbook so I would like to solve this problem fast cause iMac is my principal work station.

The drive enclosure is: VANTEC ENCLOSURE

The SSD is (120GB version): ADATA SSD

If I buy a brand new samsung external SSD, can I expect similar issues?

Thank you so much, I would love to hear what you think about all of this!

Solution 1:

If it worked fine for several months then I would suggest the case supports it. It's very possible that the control board inside the case or the cable is damaged.

If you have the technical know how, I would suggest placing the SSD inside the iMac. That way you also avoid the bottleneck of having to go over USB. There are plenty of online guides on how to do this.

I have used several of the MacSales kits, all the iMacs are still running and it took me 30 minutes at most.