This next statement of mine is arguably naive, so take it with a grain of salt.

I believe if I was in the situation you described, I’d try to work with the PM and come to an agreement on sprint goals. If that didn’t work, then I’d escalate to my manager and let them sort it out since that’s part of their job. If all that failed, I’d be looking for a new job.*

So the most stressful part of it all would be going through another interview process again.

• - The caveat of course being that I understand if it’s your first gig ever in the industry, then finding a new job just might not be that feasible. Or perhaps you’re geo-restricted. So my thought process is probably only applicable for mid-level and up