Been having tons of issues with my Z lately. Can't get a solid answer from anywhere online and I've spent hours scratching my head.

07 350z coupe enthusiasts trim 90k miles.
My keyless entry quit working all together one day, changed batterys and still no luck. At the same time, it seemed my trunk release button under the license plate and the lights around it quit working too. So I have no access to the trunk, considering I have an aftermarket speakerbox under the strut.
I took a tester to the wire harness in the trunk behind the plate and only when i shove the tester needle in the hot terminal the trunk light illuminates.
Almost as if my ground is bad somewhere.

Can the fob and the plate light and all be not working from a ground wire ?
Key fob ? Hate to order a new $70 fob and my fob I have now is still good.