From what we can see of the Red protection (Fire retard) card on the cells tops /bottom, we or I can pretty safely say it looks as if all welds are good. A tell tale sign of a bad weld is discolouration/scorching blotches. Though won't rule out a bad cell, the serial busses might be interesting to see as not enough will cause a bottleneck for current flow.
Continuity check all the internal wiring for a false signal/wire break.
Continuity check all the internal wiring for a false signal/wire break.