Hi, I have the same issue but with the Boss RV-3. There is a thread discussing fixing fried DD3s on here and it says that replacing or just removing the diode D6 can solve this. Schematics for RV-3 are here:
D6 is on the right below VR Board 2/2. Does D6 provide the same safety valve function in the RV-3 as the DD3? Would removing it bring the pedal back to life if it has been plugged into an 18V supply?
Thanks for your help and sorry for hi-jacking the thread!!!