May sound daft but, try using the earth and lives straight from the battery. I have had bad earths before causing problems. ie it powered it up but it didnt have enough kick to work the sub. easiest way would be to check the earth with a multimeter tho.???

Didnt it work fine in the Onion tho?? and nothing else has changed.

You didnt drop the amp in the toilet like you did with the Pioneer front did you??? LMAO