Hi,
So when you press reset, then press the power button, your don't see anything? No flashing amber light, or progress bar moving on the screen?
For programming in the factory, there are eMMC programmers that can program the eMMC chips before they are assembled into the machine, e.g.:
https://www.xeltek.com/resources/tec...k-programmers/
There should also be a JTAG header somewhere on the main board, which can be used for repair work and debugging.