Rat and wiring

Our key fobs quit working over night in our 2015 Prius and we also found fresh rat poop inside the car that morning. I replaced fob batteries and checked the 12v battery but still does not work. We took it to the dealer who said the ECU was not detecting the presence of the key fob even though the fob was transmitting correctly (they tested that) and said we had to replace the ECU, at $3k.

We had a rat get in the car about 5 years ago and it chewed up wires and it cost us $500 to repair and I think it more likely a rat chewed up the antenna wire going to the ECU with this problem we are having. So I am looking to find damaged wires but they are buried in the trim so unsure where to look.

I suppose I could pay for access to a shop manual but thought I would check here first. I am not thrilled about pulling the car interior apart but I am also not thrilled about paying $3k for something that might not be the problem. The dealer insists that the first step is to replace the ECU. Sounds like a shot in the dark to me.