Need help!

2009 prius. Customer was driving home. He said the engine sounded really bad before stalling and never starting again. He has it towed to toyota. They say its the battery. He brings me the car on a roll back. The engine did not run since ive got this car. The hv battery was fixed and still the engine wouldnt start. I begin to think driveline failure. So i place a socket on the crank bolt and try to crank the engine. No luck engine felt like a timing chain failure. Once dropping the drive line i take the trans off the engine. Now the engine spins free. But when i got the car the engine had less then a quart of oil and is leaking oil around where the head and block meets. So its obvious that the engines head is failing. But it wasnt locked up. Still i take the donor engine and mate it to the trans and now the new engine is locked up. I put the torque damper on the trans input shaft and it would not spin free. Am i having a mg1 failure. Has anything in the trans been known to fail that would cause the engine to not spin freely?

 

Ok so i have found that the planetary gears have failed and the ring gear sun gear and planet gears are locked together. Removed oil drain bolt and found black oil. And a large amount of metal shavings on the drain plug. My issue is a failed trans. If anyone ever experiences a engine that wont spin free. Remove the engine and trans. Seperathe them then try and spin the engine. If the mg1 input shaft isnt spinning free by hand. Odds are you have a failed planetry gears.