What a delight that you mention the contracts. That is normally the first place to look to answer such a question, although perhaps not despositive. I also understood that Boeing has insurance from Berkshire Hathaway to cover its risks. As a still further point, it may be that the battery supplier might have liability to Boeing and its customers, if it was a battery design flaw rather than a Boeing engineering issue. I imagine that all of the parties will come to some agreement. It is unlikely that any customer will want to return the planes to Boeing, since there remains a significant waiting list for them. Additionally, each airline would likely have a duty to mitigate the damages for the grounding of the aircraft by using alternate aircraft while the aircraft remains grounded. This would limit the actual amount of any damages that might be due to a rather modest amount.
Odds are that if the facts are as clear as Austin Meyer says they are, he will be able to suspend the lawsuit and have the Patent and Trademark Office reexamine the patent and find it invalid for very little money. I have done that with several patents without problem.