The Accu-Chek Aviva Nano is a great little meter but does tend to go through the batteries quick, on Sunday I replaced them and yesterday the battery light was flashing then it went blank.
Today I phoned their Careline and reported this and requested new batteries thinking those I'd used were faulty, the operator asked if I'd reset the meter lately, confused as I've lost the instruction book she said to take the battery draw out and press any key which will reset the meter, true enough I did this and replaced the batteries and the battery symbol is showing full and working fine, just thought I'd post this in case anyone else is experiencing the same problem.