Reassembling: as so many as commented, this is incredibly hard - and inexplicably so. From all appearances I’m just pressing a squat sleeve-and-pin connector down onto the female counterpart. It doesn’t look hard at all! But I couldn’t do it.
Here’s what seems to have worked for me: with my left fingertip on the cable holding the connector directly above the female, I used the spudger to press down the flat back of the connector, initially at the top and then sliding along toward the neck. I used normal pressure, and voila, when I lifted the spudger away the wretched wire didn’t spring up again. It was like it wanted to be rocked, or stroked, once, from top to neck, rather than pressed straight down.
Reassembling: What makes this so hard? From all appearances I’m just pressing a squat sleeve-and-pin connector down onto the female counterpart. It appears to be circular and therefore not needing to be oriented radially in any particular angle. It doesn’t look hard at all! Does anyone understand what the subtlety is that causes everyone so much grief?
reassembly: so far the hardest step. After getting all the connectors above board, I still couldn’t quite line up the screw holes. It finally turned out that the board was being prevented from being in its full leftward position because the edge of a flange at the top of the USB port was directly positioned against the edge of a flange on the case. I used my thumbnail to press down on the port’s flange so that it slid under the case flange, allowing the board to shift left another half-millimeter and make everything finally line up.
When rebuilding, be sure not to pin the square trackpad ribbon cable connector under the wide keyboard ribbon cable. It should be over the keyboard ribbon.
Mine was stuck too, and I did what Fred did and waited to step 35 to try and remove the cable. It turned out not to be wedged under anything, but just glued in place.
Meaning, pull the ribbon cable out horizontally. And be aware that the copper wiring is on the underside of the cable and the topside is just black plastic, so don’t freak out and think you ripped something pulling it out.