Hi, i dont understand whats going on with my battery pack
When i measure voltage across the battery pack i get 6v.
When i attach the wires to the battery pack and measure voltage i get AC millivolts, which when looked at with my oscilloscope is 50hz rough looking sinewaves.
I measured the resistance between the wires when my batterys unplugged and it is infinite.
Why does voltage go to practically zero when i attach the wires to the battery, it cant be a short as the resistance between them is infinite?
You are picking up AC "hum" from the mains. It is because the leads of the CRO are effectively open-circuit or maybe because the wires to the battery snap are faulty and not making contact.
An open cell, nothing, there would be no path for the other batteries to produce a voltage. Cells generally don't fail open I don't think, they usually fail short circuit.