On one hand when reading your question and @danj answer which is absolutely correct, temptation is to say why bother to add anything to it, since he is pointing to the only right solution here, replace topcase. On the other hand, if there are no money for a replacement part what can be done as a temporary fix ? It may be useless and maybe compromising the keyboard use at all but being the power button the ending corner of the keyboard it might work severing the traces of the keyboard one finds under the butterfly power key. Big caveat is that it’s pure speculation, if you try the solution and it screws the keyboard for good don’t blame me ;)