I'm not shure how exactly this handles the months and days, but I'm pretty sure that it thinks, it was started some days in future:
-1 year: 14.06.2017
11 months, 27 days before 14.06.2017: 17.06.2016
So we should see a reaction in some days (propably just a reset to 0)
Anyway - @rick should look into this, since there is propably a date in the future in board_date.bin...
I actually did anything wrong with my calculation, the date is around 17.05.2016! (So not in the future and therefore this is a glitch!)