I got a blue Pro1X on stock android, bought via Expensys. And I can confirm this respects the fastboot setting for NOT booting (completely) when power is applied when off.
It does load some Android kernel stuff though, but ends in a battery-charging image/ikon
Pretty strange outcome when the stock Android ROM did not suffer from this problem.
The problem only arose after installing LOS.
That would strongly suggest that it was a LOS issue introduced at that point.
I have tray for Pro1 (black) that I don't need. I broke my first Pro1 and opened insurance ticket for it. Got my money but the insurance company wanted the device. I asked if I could take spare parts from it but they said no. However, I was able to smuggle the tray 😉.
I am from Finland and I can sell it with the price that covers shipping. At least inside Europe it should be easy.