Amp cutting out

My stereo in my boat just started cutting out at high volume, it has been installed for 2-3 years and working fine, could the hot wire to the amp have gotten corroded and not letting it draw enough power?

it's a good possibility the power or ground wires or corroded

After working with it for a while I noticed that it will crank up good for about the first five minutes then it starts cutting out, like the amp is getting hot, but its still cool to the touch. Its an Alpine FRP-250 I believe.

what is the voltage are the amp terminals after the 5 min or so ?