NUC Kit DN2820FYKH boots on its own at random times

I have an Intel® NUC Kit DN2820FYKH. I only use openelec with it (latest 5.0.8 version-linux with hard wire internet). For the last days it boots on its own at random times (e.g after one day or so). Before that it worked flawlessly. The only things i changed:

1) Bios update from 041 to 050

2) Openelec update from 5.0.7 to 5.0.8

I thought it was smth about the bios update so i downgraded to 0.48. Still problem persists. Any ideas what the problem may be?

Could it be a bios issue or software (Openelec) issue?