Verified answer

If you have to you can connect your ground cable to the ground on your battery. That may be your best option if you can't get a ground anywhere else.

How long of a ground cable are you running (I would try to saty under 1-1 1/2ft)? what size ground are you using (should be equal to or larger than your power wire)? And did you scrape the paint off of the area you are trying to ground to (grounding to a painted surface doesent work)?

You may have bad ground wires coming off the battery. Check and replace or clean if necessary.

make sure the spot where you are gounding it is not painted.. if it is remove the paint and make sure its clean, and mount your ground cable tightly. also check your power and remote turn on wires, if the amp isnt turning on then it could be a problem with you power input and not the ground.