Chuwi V10HD Boot Manager Obstacle

Chuwi V10HD 3G - The micro USB OTG port stopped working - charging works, but neither the Android or Windows OS recognize any USB devices plugged in to OTG. Have been emailing back and forth with GeekBuying.com post-sales support (seller) for several weeks now. They have been responsive and helpful, but I've still hit a wall.

They want me to flash the Chuwi with the latest firmware, suggesting that the OTG driver may be hosed. But, at some point you encounter the boot screen, and I need to move the highlight over "Boot Manager" icon and launch Boot Manager.

But I can't plug in a keyboard or mouse because OTG won't work. And no OS has booted - so touch screen doesn't work. And this micro USB port is the only USB port on the V10HD.

Support wants me to find someone who is comfortable with the flashing process - but how would that person launch Boot Manager without a keyboard or mouse?

I've heard that more recent Intel CPUs have a capability to let a remote PC stay connected during the entire boot process - but I don't think that works for these Broadwell CPUs. Is there any software I can install that would let me control this process remotely?

Can anyone help?