a piece flew out during disassembly and I don’t know where it goes

Hi Mochi,

That piece goes on the top side of the console. When you remove the top cover of the console with the HDMI port facing you, locate the left-side raised plastic knob where the power supply unit (PSU) meets the metal plate (circled in red). Lift the metal plate and insert that piece underneath it by aligning it with the plastic knob. You may need to undo a few screws to get some wiggle room to insert it.

You can leave the part out if you want. I have run my console without it and is working fine. Not entirely sure about its functionality, it is probably for a little heat dissipation.