Bought a used Boss GE-7 and found this mod inside. Pedal doesn't work with a battery but works fine with a power supply. Any idea what the previous owner tried to do? :
Analog Man Boss GE-7/Pro
BOSS GE-7 Graphic Equalizer Pedal
XTS Midrange Graphic Modded GE-7
Modify your Boss GE-7 Equalizer with upgrades! Mod service Only!
Boss GE-7 Equalizer Guitar Effect Pedal Used Made In Japan | eBay