We got a Sodastream Fizz for a gift. The mechanical parts of it worked properly, but the Fizz meter didn't turn on. The back "door" was also poorly fitted and came off easily. After looking closer at the unit, it seems that it might have been a return, perhaps related to the many online reports of bad Fizz chips. I took the Fizz unit off, and there was a watch battery powering the unit. The battery in place was 2032. I didn't have that, just a thinner 2025. Same voltage, same diameter, slightly thinner. Put in the alternate battery as a lark, and voila, the Fizz meter powered up. My guess is that a bad batch of batteries was installed at the factory, or the batteries got drained during shipment.