I noticed right away when I got my NanoVNA over a year ago that it requires being hooked up to a USB power provider. A light comes on when I shut it off as if it's charging, but even after a whole night of being left plugged in, it doesn't charge? Were there two different models? I'm not complaining, I have a USB travel cube. Just curious. I think I paid around $39.00 at the time. I want to buy another to have as a backup. They have gone up quite a bit, but even if I had to pay $80.00 for another one, it's worth it.