So i recently changed out my amp with a hifonics one it turns on but the subs arent playing before i took the old amp off they were working just fine what can be wrong?
Not too mention newer Hifonics amplifiers are pure junk anymore. Not like the ones 20 years ago. So he is right either you hooked it up wrong or it is DOA.
If you still have the old amp, wire it up to see if the subs work. If they do, get another amp, as this one may be defective. Also, did you adjust the settings on the amp, correctly? That would be my first suggestion, before putting the old amp back for testing.