HDD Failed, PCB issue, what to do??

Hi.. I have a Seagate hdd which is still under warranty. I can return the hdd and get it exchanged.

However i have lots of data on that, not very important, but i wud prefer to get back everything that was there.

Hi there I am looking for a PCB for my hdd. the details are below.

Capacity. 320GB
Model no. ST3320620AS
S/N 9QF02TJ3
P/N: 9BJ14G-305
Firmware : 3.AAD
Date Code : 07125
Site Code : TK
Barracuda 7200.10

Wud any hdd capacity pcb work if i get the matching firmware and code? I see lots of ppl selling pcbs for the same firmware and code, but the hdd capacity is different. Price ranging from 10 dollars to 40 dollars, I was wondering if the PCB's firware and the code matches for a 20gb capacity hdd... Can i attach that pcb to my 320gb hdd. Pls guide.
Also i was wondering if i cud get the pcb on rent or some temporary adjustment until i cud recover the hdd. Or cheap to buy.
Please help me with the required pcb.

If you don't swap the pcb with an exact same one, it is very unlikely to work. What makes you think that the pcb is the problem? Most of the time hard drives stop working due to mechanical failure withing the drive. Swapping the pcb will not fix it.