The power IC is part of the amplification circuitry inside the head unit.
I would suggest 3 options:
1. Attempt to fix it yourself (don't do this unless you're good at soldering/desoldering, dissasembling and reassembling things, and can recognize what the IC would look like).
2. Remove the head unit and send it out for service/replace it with another.
3. If the preamp outputs still work and you have an external amplifier - you could use that. This isn't the slickest way to have a sound system operate but it won't cost you anything.