voltage controll / devolt and bad monkey bedal

[millerii]

Could be little off topic..
I got idea from beavis audio to build devolt to my bad monkey pedal and i used lm317 regulator. It works great but i notice that after i use it, something happend inside pedal and it doesn't work anymore with battery. First i thougt my pedal was faulty (never used with dc adaptor before) and i got new from warranty but second pedal did same thing.
It still works from dc plug but not with battery.
Does anybody know what possible could happend inside my pedal to cause this?
Thanks beforehand.