RN316 does no finish booting and OS install gives error "could not extracting files) last FW

This is likely a problem with the data volume, not the hardware.  It's highly unlikely to be the power supply, as it wouldn't get that far in booting.  The first best step is to remove the drives (labeling them so they go back in in the same order later) and use a scratch drive (containing no data you care about) and see if the NAS will boot and create a new volume.  If it does, and I suspect it will, then you probably have a volume problem, not a hardware one.  It is possible one of the drives is bad, so you can use the drive test in the boot menu or (better) a PC and the drive manufacturer's tools to check their health once you know the chassis is good.

If all the hardware checks out, you can ask for assistance here in recovering your volume, or at least the data from it, if you need to.  But hopefully you have a backup, in which case a factory default and restoration of data from backup is the easiest path forward.