Damage to the PCB for hard drive occurred got new pcb but obviously not as simple as attaching and done; what steps need to be done, or am I better off just using electronics from good and solder to old one
You would be best off replacing the drive. If it contains important data have this done by a data recovery professional. This will not be cheap. Such repairs are considered temporary and suitable only for the purposes of data recovery. You still have to replace the drive.
Replacement of a drive PCB is not as simple as it may seem. As manufacturers do not sell replacement boards, not even to data recovery professionals, it would have to come from a donor drive. The donor drive would have to be of the exact model number and in addition some other numbers must match. Exactly which numbers depend on the drive. Drives that appear identical may have come from different factories and have significant internal differences.
In addition there is drive specific information on the original board that would have to be transferred over. This is normally done by moving a specific chip from the original board. If this is not done properly the drive will not operate or corruption of the drives data is likely.
I have not done such a repair. I know about this only from reading and would not attempt such a repair.