No sound. Cobra 25 LTD Classic. I have power to unit. The mic keys high just not sound.My Cobra 25

Question

Cobra 25 LTD Classic. I have power to unit. The mic keys high just not sound.My Cobra 25 NW ST was in a vehicle that developed a bad voltage regulator. A large overvoltage problem caused the vehicle's battery to boil and the headlights to blow. The CB was on at the time and it's inline fuse blew. Upon replacing the fuse (and trying the CB in a different vehicle) the CB powered up and "appeared" to work with the exception of received audio. With my ear close to the speaker I can hear received voice but there is no audio gain whatsoever. Varying the controls has no effect. Do you think the audio amplifier was blown? I opened the unit and can see no "Visual" indications of a problem.Thanks,Mike