Reconnecting the antenna connector to the Airport/Bluetooth board was the second most difficult step for me. It was not just the reverse step of using the spudger to disconnect the connector.

When in doubt which of the two nearby sensors is the HD or the optical drive thermal sensor during assembly (!), look for instance at the guide to remove the hard drive. The two thermal sensors of the hard drive (see step 13 of this guide) are taped to the outside of the HD. The cable of the optical drive thermal sensor is below the HD (with the Mac mini upside down).

I suggest to list this specific type of tweezers as shown in Step 19 at the beginning as useful/recommended tool to reconnect (!) the power cable. I could pry the power cable with the blunt side of a scalpel knife. But I sorely missed something like this tweezer when trying to reconnect the cable.

The weak design of the long standoff screw (not enough material around the star-patterned socket head) has probably caused damage of the internal head during production of the Mac Mini!

The standoff screw was in my case extremely tightened and the T6 Torx screw driver could not be used anymore (due to damage of the socket head after applying too much torque during the original assembly).

I needed to use a High Leverage Combination Plier in vertical position to loosen the screw without damage to other parts. I tried to keep the rotation axis of the screw at the centre of the flat nose of the plier. Minor scratches to the screw can not be avoided in this way.

A CR2032 battery has the same size and voltage and is more readily available. But I don’t know if it is wise to it instead of the specified battery type BR2032.