Thunderbolt problem

Good day

My device is Macbook Air 13-inch, Early 2015 (Intel core i5, 8Gb DDR3, macOS Sierra 10.13.4)

I have transcend jet drive 820 with case. It worked good long time. But some days ago, during starting Macbook from the power button and before system fully loaded, I connect this drive thought thunderbolt port, system was stopped loading and after restart macbook again, thunderbolt port don't see anymore any devices.

In my city (Odessa, Ukraine) Apple service ( Restart Service Point), specialist checked thunderbolt with all possibilities (physical problem with port, restart SMC and NVRAM, connect macbook thought thunderbolt straight to IMac over the system) - any results. They don't have decision, except thunderbolt controller malfunction, but they not sure.

Can you advice what to do???