Amp shorted 12v to rca output on Alpine CDE-143bt

12v dc entered alpine head unit through rear rca output common ground,. Inspection found foil path burned and open on main board. No components seem to be affected but unit will not power up. Ground resistance between rca and harness is 376 ohm, other alpine head unit is .2 ohm. Should i repair foil path or is there a pico fuse or diode i am not finding.