Check to make sure the mechanical pins are not damaged. What is the output on UART when eMMC is plugged in? eMMC is a wear item and not covered under the general warranty as it is electrostatically sensitive. If you plug it in and it doesn’t boot, it simply means the boot data is incorrect.
- Does the erase step work and what is displayed on the monitor? Libre Computer AML-S905X-CC eMMC Flashing Steps from Linux
- Does it will boot up via MicroSD card when the eMMC is plugged in?
- What is the output on UART?
You can also boot via MicroSD card. When the board is booted, attach the eMMC and follow this. Copy and paste the dmesg output.