My Pro1 X just arrived about half an hour ago. Luckily, my device doesn't have a depleted battery, but it came out of the box at around 10 to 15 percent. I'm guessing some units were close to dying when F(x)tec checked them, and they fully ran out during transit.
Please don't disassemble new and intact phones if you don't have to. The Pro1 is easier to disassemble than other phones and it has a lot of potential for modifications (like I have two USB C ports) but it's not worth the risk damaging some components while opening it up.
I know it's sad but please let it get fixed by FxTec, even if it takes some (more) time.