Hi,
I agree with @Relign.
It looks like you have lost half the Din pad at the end of the array, you have probably tried to solder to the bit of track that was left.
Instead of using your magic DMM probe, use a magic small screwdriver to push the Din yellow joint and see if the same happens.
OR
Forget the first LED element and solder to the next Din after CAREFULLY removing the first LED element.
Tom... 