Hello,

On the photo n°3, under the conductive strip to the right of the transparent screw that clamps the 2 conductive strips, there are 9 horizontal tracks on the PCB.
The 6th track from the bottom joins track no. 4 (row 4?) on the conductor strip to the left of the transparent screw.
On the PCB, this track splits into 2 others tracks, of which the horizontal one on the right has a solder bridge up to a brown solder joint. This is probably where the problem lies.
Furthermore between track n°7 and n°8 , it seems that another bridge of solder exist.

Cordially.