HDMI provides power - that's how old chromecasts can work without a separate power plug.
The comment about NPNs and PNPs is garbage, but there is a design fault with the board - it shouldn't allow HDMI power to flow backwards into the motherboard when the motherboard shuts off. That would likely cause a power rail sequencing issue on the board or SSD, leading to latch-up of various ICs, and non-detection on the SSD on the flowing bootup
The comment about NPNs and PNPs is garbage, but there is a design fault with the board - it shouldn't allow HDMI power to flow backwards into the motherboard when the motherboard shuts off. That would likely cause a power rail sequencing issue on the board or SSD, leading to latch-up of various ICs, and non-detection on the SSD on the flowing bootup