Multiple warning lights and no shift to D on my Gen 3 after battery switch

Gonna take awhile to get to my question. Please be patient. Figured it best to describe what's been happening in case its relevant.

The car has 245,000 miles on it. The engine was replaced 3 years and about 15,000 miles ago by my shop, after head gasket failure of the original. I don't know the age of the new engine. It was not a rebuild. Car has been operating okay since. It did use a quart of oil every 1,000 miles on freeway travel, but my freeway travel dropped to almost zero about 2 years ago, and the car stopped burning oil. For about two years now, I've done mostly local travel (still getting 45 mpg) though I did put 400 interstate miles on it a few days ago. Car behaved well this last long trip, but again burned oil.

Check engine light turned on a day or two after the 400 mile trip. My shop, which does good work but may be straining a bit with a hybrid system, texted:

"cylinder 2 is a persistent misfire, but did not follow a coil or a plug swap. Tried pressurizing the system and scoping the cylinders, and it looked alright. Need more diag time to pull the EGR cooler, since there is a code for insufficient EGR flow, which may be the source problem."

The shop estimated $600 plus part to hang a new EGR. Given the EGR code, the known problems with EGR, and the oil burn history, I told the shop I would just bring the car back to my garage and DIY the EGR, hoping that would fix the check engine problem. I'm not close to a mechanic, but I can usually put things together after taking them apart, and there are good resources on this forum to help me take off, clean, and reinstall.

However, here's the problem: when I went to bring the car back from the shop lot, it would not go into Drive. It did go from Park to Neutral. Plus, multiple lights on the right side dash lit up - charging system, brake, check engine, open door, ABS, and power steering warning lights on the right side, and traction control on the left.

The 12v was last replaced 7 years ago. It was indeed failing - it would unlock the doors but didn't have enough juice to unlock the hatch. So, thinking the failing battery was likely the reason for the christmas tree dash, I swapped in a year old battery from my son's Gen 3 Prius. Nothing changed. Car would leave P for N but not go to D. Same warning lights. I turned it off and on a few times and kept trying. No luck.

Disappointed, I put the battery back into my son's Prius- and got the same warning lights and refusal to go to D. However, when I turned it off and back on again, everything worked the way it should on his car.

Any guesses as to going on with mine? Appeared to be a 12v problem, but the new battery didn't fix it. Is there some special step or sequence I missed when replacing the battery? Some magic digital code I can reset? Is the EGR failure code somehow related? Given the mileage, I don't want to put a lot into the car, but now is not the time to be buying another. Fortunately I do have another vehicle I can use until the Prius gets fixed or takes its last trip. But the AC still works! I can't just give up.

Any thoughts or suggestions? Thanks
Ed