The fine pitch 32bit microprocessor was placed on the prototype device.
The testing was done to ensure that there were no bridges between the pins.
In the photo a tall bolt is visible. The bolts in the photo will not be present in the end user devices. The bolts are added on the development unit to allow permanent connection of power onto the device. On this development device long extension cables are added to allow the rechargeable battery to be located further from the PCB.
The end user device will not have any of the wires, and the battery will be placed on the top of the two nuts.