I understand that in scrum developers do some QA, but in the last several sprints we've been doing almost nothing but QA.
We've brought this up to management, but they insist that that's how scrum works (and I know it's not!), and that it's temporary (which it doesn't seem to be, either).
Morale is low among the developers, and management is very sympathetic but very unhelpful. Just to be clear, we've communicated that we are not willing to go on like this.
How can we fix this, without actually quitting?
To answer comment questions:
We're QAing new use-cases that hadn't been thought of, and stuff other teams did. Also, the occasional scrap we do develop is required to undergo days and days of QA (including related QA documentation)
The product owner decides what goes into the sprint. We get to give an estimate how much will be done,
Clarifications regarding the amounts of QA we're doing: there hasn't been a lot of QA done before, and we're making up for it. What was done was pretty basic, and they're using us to do more thorough QA. Again, we're also doing QA for the little bit we do get to write, but each bit of development takes a lot of QA time because: A) There's a lot of mandatory documentation, B) Most of us are developers, C) We're highly demotivated.