Here is where the reassembly process diverts from the exact reverse order to the disassembly process.

The reason for this is the need to get the upper aesthetics panel on before the lower aesthetics panel, so that the graphite paper can sit in the right place, below the lower aesthetics panel.

So we start by reconnecting the flex cable connecting the battery to the mainboard.

Again, we do this in the same way as reconnecting any flex cable, align, press down with your finger, and listen for an audible click.