I just tried Solid Explorer and it told me I needed to downgrade to use it?
I have never tried to copy files using a USB stick but I can certainly give that a shot. I can't be that hard to figure out.
From what I can tell having messed with this for hours, I am expecting to see files in /storage/emulated/0/Android/data. So far every directory in the data directory appears to be empty. Even if I could attach a USB stick to the x5, I honestly don't know how to get to the directories I need to.
Doing a little research, there is some way I can connect the x5 directly to my laptop and that should give me access to the entire file system. I have a Mac so I am not sure if it's relevant but when I connected to my laptop, I didn't see a disk pop up as I expected it to.