I read the section of the service manual that describes how to get to the amplifier. It's really not that hard. Pull back the carpet at the top of the passenger side footwell. Remove the styrofoam block and you'll see a metal plate. There are three black plastic nuts holding it in place. Two of those are at the bottom of the plate below the fold of the carpet. A small ratchet can get in there and unscrew the nuts.

I've attached photos of what I found on the plate. There is a LOT of stuff on there and a LOT of wires. There are two plastic wire harnesses that plug into the side of the amplifier. If you're going to replace the amplifier, I'm guessing you have to disassemble these harnesses, right? There's a metal bracket holding the amplifier in place. Screws go through the bracket and into the side of the amplifier. Are these screw locations standard? Will any replacement amplifier have screw holes that align with the ones in this bracket? If not, how have others mounted replacement amps?

It almost looks like it would be easier to run new wires to new speakers and a new head unit than to mess with that amplifier.