Lights out on Passport Wireless SSD?

I tested my unit a couple of times with one photo and it worked fine. I am now trying to transfer 128GB of photos using a memory stick, direct, and while the stick’s light is flashing and the SSD light on the unit is flashing, the 4 lights in the light bar are dark, no blinking at all and the transfer has been going on for an hour (I hope). How can I tell?
Thank you in advance for any advice.

There is a dedicated power button, along with an SD / Battery button that is used to check battery level, or start copying the contents of an inserted SD card!