If she endorses Biden, she’ll be dismissed by progressives as a fake.
If she endorses Bernie, she’ll be dismissed by moderates as a loony.
If she does nothing, she’ll be dismissed as bitter.
If she endorses Bernie, she promotes a base that designed and pushed a wildly sexist agenda against her and engaged in constant misogynistic attacks on her team.
If she endorses Biden, she promotes a base that agrees with almost none of her stances.
It is a garbage, garbage situation.