Hey guys!

So I've had the Boss ME-25 Multi-effect for around 2 years now and never had a problem with it. Now it randomly started to boost the volume on it's own. I choose my preset, start playing and 5-10 seconds after, the volume boosts (always to 84-85). And sometimes, the preset changes or the LCD displays the little '' -- '' sign, as if no presets were chosen.

Any idea on what might cause this?
Ibanez SIX28FDBG
ESP EC-1000 Deluxe
Ibanez AGR73T
Ibanez RG350DX
Ibanez AW
Peavey Triple XXX
BOSS pedals : TU-3 -> CS-3 -> NS-2 -> RV-5