I Have seen the chain go a couple of ways. One is it starts skipping over the pumps drive teeth. The pump turns but not very well, that seems to put a lot of trash in the motor. The other is the upper pivot fails and everything comes undone.

If the balance shafts are still good you may be able and want to keep them. With a fresh chain and guides they will last a long time.

It sounds like your motor may be OK. AS I Thought about things I realized that the filter would not have any trash in it if the pump stopped. If it was a skipping failure it should. I would also drain the oil and see what you get.

When you get it running the filter test would let you know if the motor is eating itself.

Kevin