Repair/teardown of DGT's Pegasus online chess board

We believe that the play area/sensor PCB may be shared with DGT's Centaur

Fault

Inconsistent piece detection (absent and spurious) on two squares.

A thin board/sensor PCB covers the entire play area.
The power/interface PCB is connected to the board/sensor PCB by a ribbon cable.
The board/sensor PCB is not accessible without delaminating the board surface (a polyester sticker?)
We used heat (a clothes iron) to assist in removing it (the board surface.)
A light pipe array (polycarbonate?) is screwed into the black plastic ABS base at the centre and four corners (screws inaccessible without removing the board surface.)
The rear surface of the board/sensor PCB holds the play area control electronics.
There's an IC on the rear surface of the board/sensor PCB (part of the control electronics, acting as a sensor interface?) Possibly R5F51303ADFL
The rear surface of the board/sensor PCB also holds the LED array, LED drivers (8xSTP08CP05) and interfaces to the light pipes (to bring the LED light output to the board surface.)
There are row/column tracks on the front and rear of the PCB running to each square - inductive piece detection (essentially very short range metal detection.)

There was a broken track at the end of a row/column leading to inconsistent/missing piece detection.
The faulty PCB track was repaired, and following board calibration (a normal process of using the board) the board seems to work as intended.
New board artwork was maunfactured and attached.