Need help with a 2000 Grand cherokee with a crank - no start issue
I have read searched forums here and elsewhere and have tried everything
suggested . I own/owned several other grand cherokees with similiar issues
so I am famiiar with trouble shooting, but am stuck at this point and hoping
someone can get me to next step or help me see what I am missing.

I did a top end rebuild / head gasket on this jeep and did a bunch of " as long
as I'm doing that I might as well ...... Was running great and I was going through
fixing some other minor things when it was dead when I went to start it. I dont
drive it often so didnt think much of it, jumped it , drove it . Dead again next day.
Charged it overnight . Started , drove it - dead again next day. Pulled battery
and got it tested - they said it was good. So figured electrical draw. Pulled it into
garage and hooked up volt meter across negative terminal and pulled fuses one by
one to see if anything changed and check fuses as well. Went through all fuses ,
did not see any sig change in draw and all fuses were good. Went to restart and
crank - no start.

I started going through process to figure out whats wrong - fuel pump was not running.
Put gas down intake, no start. Checked coil pack- no spark. Also lost all gauges.
So now on the path that its electrical issue.

NOTE - I have the luxury of having a friend withthe same model so when I say " swapped "
a part, it means I took the working part of his jeep and put the questionable part onto his to test
both ways.

I read through forums and did some searches and went though the following :

swapped can sensor
replaced crank sensor
replaced fuses under hood and in fuse box
swapped relays under hood
replaced battey bc it turns out battery was bad even though Auto zone said it was good
swapped ECM ( I know chip key/ pin wont match, but it should start and run for like 3 sec )
swapped skim reader
replaced ignition started switch
swapped gauge cluster
traced as many wires as possible looking for broken wires

I attempted to hook up OBD reader and said cant connect- but worked in the past.

SO whatever the problem it seems like it is preventing communication with the ECM
also.

I had read that if it is the crank sensor, unpluging the crank sensor and you will get gauges back which
it did not.

I am leaning toward something with security system lock out and I am familiar with the chip key - skim
module - ecm getting out of sync and having to be reprogrammed but ususally in that case the car will
still start but just shut down right away.

Keeping in mind that I drove it into the shop and it was fine - pulled fuses one by one - and then all this
started , does anyone have any suggestions or directions to go in ? I am right at the edge of just sending
it to the junk yard or selling for parts , but now its kind of the principle and I would like to figure it out.

Short list of suspects but not sure how to test or if I can just replace :

1. ICM - ignition control module
2. immobilizer
3. A part that I replaced was bad out of the box like the crank sensor

Sorry for the long post - hoping someone else has dealt with this