2016 SRX won't start and liftgate won't open. Have full electric to everything else, no blown fuses, battery at full charge and tested by 2 separate sources, grounds all good. Liftgate won't open at the switch on door, rear hatch, or by remote. When you hit the remote, the tail lights flash, but no click. When you try to start the car, the dash goes black. Been working on this for weeks, replaced the short battery cable and power distribution plate on the battery with the fusible links .Getting no communication with scan tool, no crank, just the sound of the wheels spinning in my mind. Thank you for your thoughtful responses in advance.

You need to fix the network. What is total impedance (ohms)?

How was the battery tested? . . . and by who?

How were all grounds checked? . . . and by who?

This tells me that the BCM is probably working.

Do all of the power ports/cigarette lighters still have power?

Does it stay black, or does it go back to normal after the start attempt is over?

Why was this done? Was there a clearly diagnosed problem with these parts? . . . or were these replaced first before the problem started?

Does the scan tool get power from the OBD2 port?

not sure how to test that?

I'll start by saying this happened after the car sat for 4 days while we went camping. I started the car, took it to get it washed, took it to the store, then to see my wife at work, then to look at the new Mustang at the dealership, where it ran for a few minutes while I looked. Went to back out of the parking space and it stalled, which it has never done before and wouldn't restart or take a jump. Had to have it towed home and it'* been here ever since, trying to diagnose the problem. I'll answer your questions, taking them one by one:

1 battery was tested by my friend who runs a mobile service with a battery tester with a load tester and printed out a result sheet and the same from NAPA, both test
the battery at over 600 cca

2 loosened the contacts, retightened, and checked to make sure they weren't drawing amperage by myself. Is there a better way? I'm not a mechanic, just been working on cars and have enough knowledge to get myself out of most problems I've run into over the last 50 years or so. Cars are getting so much more complicated
that my skill set is becoming more limited. Just trying to save myself hundreds/thousands by taking it to the dealer.

3 will have to check the ports/ cigarette lighters, haven't do so yet

4 screen goes black and then about 15-20 seconds later comes back on with startup screen

5 have been reading posts about battery power issues and these items causing many problems, so replaced them thinking the power wasn't getting past the top of the battery. These items were replaced after the problem began

6 finally, the scan tool shows a code u0100, something like unable to connect to server/ecm, not sure the exact wording

went out and checked the acc/lighter port and they both work up front. Also checked the OBD2 port and it'* getting full voltage, but not connecting to the ecm

That needs to be fixed. What tool you using?

I just use one of those Fixd portable scanners that hooks to your phone, but my friend used the Snap On scanner and couldn't get it to obtain a signal

I think it'* time to measure voltage on both sides of the fuses related to the PCM, then work your way from there depending on what is found.

Easy way to test fuses while they are in place. A test light or meter works well and you can do a full box of fuses in a minute or two.I like a test light myself.