i dont think your ECU is fried or damaged since mine got fixed and im driving it currently. start there and report back.
THIS happened to me:
parts store put my battery in backwards and had to pay for the following to fix my is300.
-MAF ( mine got fired )
-main relay fuse ( under the hood its a big fuse )
my car was fixed at a toyota in 2 days , and havent had a issue since. the parts store had to pay $1500 to do those two things hahahaha. be careful when working on your car , and letting others touch your car.