Leave it alone for a few days. Sometimes it goes better when you go back to it. You have to agree at present it makes little sense.
We learnt years ago to leave a difficult problem for at least a day or so. We could usually come to grips with it much faster the next time. Has something to do with objectivity being restored I imagine. Or perhaps even the subconcious mind .
To keep at anything when it has got to the point of frustation or any other emotion is never very good. Emotion will always or usually defeat or distort the application of logic. You tend to get locked into a fixed mental loop.
Very few things in my life actually where not solved by applied logic. There have been a random few times even after the problem was solved it was not really logical. Very rare though. Usually put to rest by an unknown in the general equation left undiscovered.