Unregistered gpa executed registered release deed is void ?

Under the Indian Registration Act, 1908 an instrument of a power of attorney is not compulsorily registrable. Nevertheless, the Calcutta High Court has held that the Court is not bound to presume its genuineness unless it is registered. AIR 1916, Cal. 979. A power of attorney through unregistered is valid, but the geneuineness of such an unregistered power of attorney will not be accepted by the court as a matter of course. If its genuineess is questioned it has to be separtely proved. 

As per latest supreme court judgement (Bench prersided over by S.B.Sinha J.) and the provision contained in section 33 of the Registration Act 1908, the General Power of Attorney as you discribed is inoperative in the eyes of law as the said document is nonest in the eyes of law save and except, the other extraneous purposes as per provision of the Section 49 of the Registration Act 1908. So the transfer as allegedly made through the said unregistered General power of attorney never creates valid right upon the transferee. So you have to find out other remidies  to get the transfer valid.