Are you out if a bats slip from your hand and flew into striker’s wicket?

Question

So we had an incident where a batsmen was struck on his head and his bat flew back leaving from his hands and went into his wicket.

Is it out?

Answer 1

Assuming an appeal is made, yes. Law 29 The wicket is down:

The wicket is put down if a bail is completely removed from the top of the stumps, or a stump is struck out of the ground [...] by the striker's bat not in hand

and Law 35 Hit wicket:

The striker is out Hit wicket if, after the bowler has entered the delivery stride and while the ball is in play, his/her wicket is put down by either the striker’s bat or person [...] in any of the following circumstances:
in the course of any action taken by him/her in preparing to receive or in receiving a delivery,