Synology DS 1815+ will not power on

Hi Synology DS 1815+ will not power on and it is out of warranty.

I have seen online that a soldering a transistor and/or failing that replacing the psu would fix it.

Can anyone share a guide on steps to soldering the transistor as well as replacing the psu, and details where a compatible transistor and psu can be purchased?

Thanks in advance, any help would be appreciated.