I bought this about 2 months ago and it never really works. You press the button and it lights up blue for a second and beeps then shuts off. It has worked once but after testing it out had 3 completely different readings.
In general, this thing works ok. I have a breathalyzer in my car and wanted to make sure that I never tried to start my car with a BRAC over 0. There was one time when this device told me that I was at .02 and immediately after, my car told me that I was at 0. There was another time when this device told me that I was at 0 and my car told me that I was at .02. Unfortunately, I have had some problems with this little unit. I trust it to a certain degree, but it's not as accurate as I had hoped.
I just received the BACtrack S35. After inserting batteries, I pressed the start button and a blink of blue light and nothing happened. Pressed for longer, there was still nothing. I am frustrated to find this product is completely not functional.