453 - Radio not turning off, need help!

Hi folks,

I was swapping my stock (basic radio) to a aftermarket head unit. The head unit didn't seem to work,so I put my OEM one back in.

Now, my OEM head unit won't power off with the car and if I manually turn it off it's like it's constantly resetting(loud volume).

I am at a loss. I've checked several fuses, nothing is blown. I've disconnected the battery, didn't help. The battery is new, replaced two weeks ago.

Help lol!