A Raspberry Pi Compute Module 5 motherboard was reverse-engineered by sanding through the board layer by layer to reconstruct full KiCad schematics and the PCB layout. The project started by depopulating all components, measuring passives with an LCR meter (and ferrite beads with a VNA), then sanding the motherboard one layer at a time. Each exposed layer was imaged using a flatbed scanner at 9600 DPI and traced back into KiCad, which made it possible to reconstruct the full 10-layer stackup. It is what’s known as a 2+6+2 configuration since it has four layers of microvias: layer 1-2, 2-3, 8-9, and 9-10. There are buried mechanical vias from layers 2-9, and standard through-board vias from layers 1-10.