2020 Rav 4 ECU Failure

Ive had my 2020 rav 4 hybrid Cruser for abou 12 months now, (second owner since brand new) the warranty just ran out last November for the engine. About 4 weeks ago the car broke down on me, so I sent it in to Toyota and after about 4 weeks of diagnosing they have determined that the 12v battery failed and shorted out the ECU, the car was serviced 2 days before it broke down by Toyota with the report stating the battery was checked and all okay, this car has only ever been serviced at Toyota and they are telling me its going to cost $3400 to have the ecu replaced.

I think this is very poor service by Toyota as its just out of it warranty period and its failed an ecu already, im at a bit of a loss on what to do, has anyone had any luck with a similar situation?