First thing I would do is to reformat the drive with the (write zeros option). This will map out any bad blocks you might have. Then reinstall a system.
If the machine will start from the optical drive with the Data rescue disk then it should start from a Retail system disk or the original system disk. Gray system disks made for other machines will not work. Please tell me about the disks you are trying to use.
You can also access the disk via another Mac in Target mode.
Charging the machine will not recharge the PRAM battery