Baffling P3102 and C2300 Fault

Hey all! New posting member, long time lurker. My Prius has given me some trouble recently. To make a long story short, after an engine/transmission swap on this car to solve an oil burn issue, this car now gives me the triangle of death, the P-lock message on the MFD and the above two codes. Car ran and drove fine before the swap save for the excessive oil burn, started up reliably and never complained about anything. The swap was done by yours truly.

The car itself is a 2005 base model, has 270k on the clock, but the new engine/trans had about 90k confirmed running and driving before pulled from donor vehicle (A 2008). All harnessing is good and I've tried 5(!) Different shift lock actuators, all of them functional since the car will go into neutral (when manually put into park) but refuses to go back into park and also will not enter "READY" mode.

The codes (with INF) I pulled were:
C2300, 10, 0
P3102-581

I've been scratching my head over this one now and I'm about ready to swap over the HV, transmission and power control ECUs from a different, specifically 2005 donor. I wanted to make sure I didn't miss anything before I start chucking parts at the problem since the diagnostic tree is super vague in all sub codes...


Thanks for any advice or pointers!!

 

Since initially posting, I've tried more things in an attempt to corner the issue, or at the very least eliminate some unknowns.

More things I've tried are:
- checked harness between p-lock actuator and fusebox in engine bay, seems to check out.
- checked PCON fuse and performed the reset procedure for it. No luck.
- I do have a spare harness from the donor car that was undamaged and I've familiarized myself with the pinout of it generally.
- verified that the original harness was not pinched anywhere during the engine swap surgery.
- tripple checked 12v power. Sits steady at 12.7vdc with headlights on.
- had the hv battery recharged since the car had not run for so long. Resting voltage is at about 208.9vdc.
- inspected the hv battery for any corrosion on the terminals since I was already in there.


There are some Things im curious about.

1) If I swap over the 3 computers mentioned in my original post (engine ecm, trans control ecm and hv ecm) will I have to perform the sync procedure for the immobilizer and engine ecm? I plan to source all three aforementioned ecm's from the same donor car such that they don't need to me synced up to each other since I know those are all paired.
2) the vehicle has always had (what I think to be) a gremlin where if the parking break is NOT set, the vehicle will not entirely shut down and refuse to surrender the fob. It behaves very similarly to a failing instrument panel however if one were to set the parking break and power the car off it obeys the command and shuts down. Is this a case of "its not a bug, its a feature" and this is common, or...?
3) what the maximum safe operating voltage might be for the above computers? I ask this because it has recently occurred to me that one of the booster boxes (I have a few different ones for different tasks) I had been using was providing something on the order of 15.6vdc when providing power and I'm 80% certain that this particular booster box was hooked up to this car at some point while it was in storage, and was used to wake it up to verify milage.
4) Could the above have killed or harmed one of those 3 ecm's?

Any and all input greatly appreciated!