How to correct wrong amount entered in matching PO form for a CM?

Hi there,

We are using 11.5.10.2.

A user entered a CM with $50 but when he tried to match it to PO, he entered $500 by mistake.  Right now the invoice is on hold: Total of invoice distributions does not equal invoice amount.  There is nothing we can do, can't delete it or cancel it.  We can't release the hold manually either.  We tried to use "correct price" function in that form but it only allows to enter negative amount for CM (so to increase the absolute amount, not reduce it).

Please advise what we should do in this kind of situation.  Any suggestion or recommandation is appreciated.