Reverse Polarity troubleshooting - power management ECU?

Last year my 2013 Prius C sat for months while I worked from home (second car) and was not regularly started. Eventually when I went to dewinterize I had to jump start and the battery didn't hold the charge. No excuses, just trying to do too much at once, I wasn't paying attention and reversed the polarity. Blew some fuses, melted some plastic on the terminal, and damaged X number of yet unknown components. Convinced a mechanic to make a house call and he told me just one more fuse and I'm all good. Not so. Bought new battery and it continued to get drained. Codes: C1241, C1311, C1464, C1465

I let it go for the winter and tried again. This spring, I began driving short trips and disconnecting the auxiliary positive when I shut off. Did well enough, but SRS warning light was always on, and the DRL stayed on even when the car was shut off.

Because I'm curious and a glutton for punishment, I ended up acquiring used ECM and Body Control ECU, and went to work. Finished today, and turned the key - got some new codes - C1259 and C1310 - and a host of warning lights. But the DRLs were off, so I accomplished a tiny step forward amidst some leaps backward. Based on the codes I'm considering finding myself a used Power Management Control ECU and climbing back inside the dash. Acknowledging that I'm in way too deep and probably wasting my time learning on the job, am I way off base? If I can find a salvage unit for $100 or so is it worth the money and the day of work to just test the theory? Or, are there things I should do first, such as replacing the newish battery that I've abused for a year? Do I need to flash the newly installed computer?

I'm kind of enjoying this process and I'm dead set on bringing it back to life, so I'm open to all suggestions. I'm aware that I deserve all the ridicule to come my way.