connected an amp no sound

I am trying to install a car amp Jensen 4-channel 760 with an old aftermarket JVC S890, my first time installing an amp but not the first time installing a basic aftermarket car radio. Connecting the speaker wires seem pretty straight forward but there is no sound coming out of the speakers. There is power on the radio and a played CD and radio FM stations showing music signal from this JVC. The 4 RCA output for left and right speakers go into the amp 4 channels. The blue remote wire is connected. The amp green LED lit up an indication of power but the green light dims and lit up brighter at the interval of about every second or half a second. That is a bit concerning. Ground wire is connected to the meta harness that supposedly connects to the car chassis. I have even tried connecting to both the meta harness and seat belt bolt but I just black taped the wire to the seat belt bolt for testing purpose. I have turned up the amp level half way just to test for sound but nothing happened. Any suggestion? Thanks.

Ummmm.... you have the amplifier connected to the ground wire in the Metra harness? Bad, kel... BAD! ALWAYS connect SECURELY (and ESPECIALLY the ground of an amplifier) before "testing". Find a proper ground, (and NOT a seatbolt) then return.

I tried using seatbelt bolt because it has been recommended by some and crutchfield from reading but I didn't secure it. any location recommendation with such a short ground cable? I got the amp kit. It will be under the passenger side seat.

Take off some panels, pull back the carpet, scrape the paint to bare metal, ground it some where to the metal chasis (with a self tapping sheet metal screw and a star washer) , silicone over top of it to make sure it doesn't corrode, and that would get you a much better ground than the seatbelt bolt. Do not just attach it a bolt somewhere.MECP Advanced

Make your life easier and buy a DMM.

problem solved. you are right. it was the damn ground. the light power indicator is lit up without any dimming. it's a huge sound improvement with an amp. thanks for the help. do you think a pair 6.5 woofer to replace my current 2-way speakers in the rear can improve tighter bass? i am trying to avoid a sub in the trunk to save space.