I did what you suggested..

The only thing I'm wondering is if you shorted out the RCAs somehow. Try switching the RCA's to another output on the back of the deck, if you have more than one set.

If that's not it...you will have to add pieces of the system one by one, starting at the deck, to see if you can troubleshoot the problem. Very Odd.

Good Luck

A couple of things -
*The battery could not be fully charged and starting depleted the battery reserve. Recharge and try again. Battery should read ~12.5volts fulled charged and not drop below about 10.5-11volts as you crank.
*Disconnect the deck and try it again. You may have cut/pinched a wire that grounded some part of the start system, There may be a connector to the deck that is not connected and your safeties are not letting it crank.

Sounds like blown subs, in the process of completely dying out, or a loose wire, possibly inside the box or from the box to the amp. Have your subs tested at a sound shop, or using a multi-meter, check for resistance across the sub terminals. An open line indicates a blown sub.

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check the ground wire or the fuse behind the wireharness on the radio.

Subs are subs, they come with no wiring. You need an amp and all necessary wiring to get it bumping. What type of deck do you have? Where will the sub be placed? In the trunk? Amp install is easy. Also suggest purchasing one of those amp kits for $20-$30, makes it a bit easier.

there is a wire that you must connect behind the radio deck that is blue, this is the remote wire, this goes from the wire to the amp and is what sends the signal that tells the subs to beat/make noise
you will want to run the wire from the amplifier to behind the radios wiring harness. this should fix the problem.
you also mite want to chek the settings on your deck and the volume settings on the amplifire

I agree with what you think it might be. I really think its the deck that is bad and you should be able to take it back for a new one. Have you tried unplugging the RCA cables to the amp to see if that stops it? That would tell you if the amp is backfeeding or doing something weird.

reinstall the factory radio use a digital volt meter to see witch wire supplies voltage when radio is turned on and off, note placement on harness then verify this wire is hooked up on the output side aftermarket harness you may have to jump it to get the maps to turn on. tip you can carefully pull unused wire from harness example (dimmer wire orange white) and move it to the position needed to keep it a clean install .

check the wire inside of the sub box

This problem has many causes... but try this one... often when a faulty subwoofer speaker is to blame this test will tell you. Connect another speaker(any speaker) temp to check if there is audio still to the sub. Keep the levels down to ensure you dont go on a trail of destruction.
The spider wires from terminals on the speaker to the cone may be intermittent. I have seen this a lot on all types and makes of subwoofer driver!! This a common failure and can often be detected by tapping the speaker cone when it does the cut out thing. If it starts up, and they often do..., then you probably have intermittent spider wiring to the cone. A GOOD “Hi Fi speaker repair dood” can help here and replace the spider wires for you and save the expense of replacing the driver.
This is just one solution to the problem you are having.... there are many more..... and you should try this FixYa and see what happens. If you cant tell WTF then hit me back up here again. I work WITH YOU, to get the problem out for you.

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