STRANDED ...---... 2005 Prius dead-in-water, in desert rather...

Desperate- stranded off grid- please help ...---...

So I messed up- in freezing light snow, strong wind conditions of high altitude Northern NewMexico- I reversed polarity while attempting to jump start my only ride- 2005 Prius (eyes watering from freezing wind and snow, feet freezing, with jumper cables black/yellow stripe on black (not red/black)- confusing while fazed, but my fault....) No snow entered fuse panel. Living self sufficiently off-grid on solar- I'm technically capable and know my way around a multi-meter.

Symptoms- with new 12V batt- zero power, indicator lights, bells, etc. Clearly, there's no on-screen diagnostic system, etc.

Context- 12V battery dead 2-3 days already, but I had a brand new replacement at ready (good V,) and the current 12V batt had jump started well under similar circumstances several instances previously, (though not as inclement.) The HV batt seems good never trouble. Had replaced inverter pump previously, also MFD/screen as well. I was all ready to install new batt and batt remote cut-off, but just wanted to make town-run first and let weather warm a bit first. But jump starting old batt was easier than crawling into trunk area to deploy hard-to-reach manual hatch switch, then swapping batt.

Anyway, I was stumped as to why the running lights were on upon connecting a regular sized, well charged 12v battery, which was previous successful MO, but I didn't deduce the reversed polarity, leaving batts connected for maybe a couple of minutes. Also the key fob batt had run down some time ago and I was just manually using key and inserting fob for some time.

Troubleshooting- Installed new key batt and the new 12V batt, checked numerous fuses and fusible links: AM2 several others and fuse block under hood (same voltage both sides of block.) I checked fuse and link in trunk, and fuse panel in cab- from all 3 locations checked any fuse that referred to HV system, ignition, immobilizer, etc.

Is everything ruled out except for ECU/ECM?

If ECU or ECM (which?), if I just order one online for~ $24- $200, do they have to be programmed? I'm far from any city and towing/pro-repair- can't afford.

I'm prepped for food etc. for a good while, but I really need my ride. Thanks Much to all who went the distance with this post, very best wishes, and PLEASE HELP!