here is the picture with what you should measure.
You simply need to plug the USB, nothing else
you can use any ground point on the board. the easier one to use is this one. square pad in the connector.
Thanks J4bberwock! I tested the chip as described, and on the non-working blade I do get 5V on the input, but no 3.3V on the output. Just a 0v read.
The working blade shows the correct 5V input and 3.3V output.
I'm assuming this means that the AME8805 is fried. I'm certainly no good at SMD soldering, but do you think I could have this replaced by a pro? Could this failure have caused damage to any of the other components?
Thanks for any other info. Hopefully I can get half my money back from the seller.