Batteries always come depleted. Compartment super difficult to open.
I have worked with about 2 dozen of these devices for our team and there are 2 critical flaws.
(1) They have a microcontroller in sleep mode constantly sipping from the battery to wake up when you hold one button. But their sleep mode is not good and these things drain their battery in a matter of months, even when off. This also means that devices that have been in stock (brand new) stand a 50% chance of arriving NOT FUNCTIONING. This is an out-of-box failure, straight up.
As another note, they had space for a bigger battery, but they didn't make use of it. So we have an odd ball small 1620 battery when a 2016 could easily fit. Heck, if you can fit a 2016, you could fit a really common 2032 and the device would last for years!
(2) The battery compartment on about half of these is extremely difficult to open....you end up scarring the plastic really badly to get to that depleted battery.
If there was something else on the market to compete with the temp trainer then Finish might be motivated to improve the design flaws. But there isn't.... Buy a LOT of 2016 batteries and be prepared to get a DOA unit.