It's very likely to not blow up. The engineers who studied the issue all think it's much more likely to work just fine with lower thrust levels.
Why not just fly the crew back in it then? "likely to work fine" is not sufficient level of certainty for NASA (anymore, because of bitter lessons). They need to be able to quantify the risk. And this is not possible, because an uncertain amount of damage was already done inside the thruster dog houses when they overheated and some material in them melted, and they cannot be inspected.
What guaranteed the unmanned return was that when they did new ground tests with the equipment, the damage was not consistent between tests. This means they cannot model what happened, and they cannot inspect the current state of the dog houses, meaning that no sane engineer will sign off on it, even though the damage is probably not very large and they can prevent future damage by using a less aggressive flight plan.
> is not sufficient level of certainty for NASA (anymore, because of bitter lessons).
It never was. If you trip into a known failed safe situation the mission rules immediately change. This has been true since manned space flight started.
