Im guessing the 3.6 / 3.4 volts were read from a charger . The cells charge to 3.6 so the reading is normal. Then drops to 3.3 with load.
5.4 volts would be the two cells in series. It should read closer to 6.6. 5.4 is to low. The 0.0 reading i dont know. Maybe you read some empty pins.