Hi Kiran
I am also facing similar problem with P89c61x2BA when I try to reprogram through ISP using FlashMagic.Iam forced to switch over to this device due to non availability of P89c51RD2BA. Did you solve the problem? If yes, please let me know the details. The device gets into ISP the first time with factory set defaults. But later even your trick of resetting with power ON doesn't seem to help in my case.
Regards
Santhi