Dead disk in LS slot on 520

Hi all,

I believe this is already a settled matter, but, it never hurts to be
certain.
I've got a 520 that we just moved from a building about to be demolished.
The client had forgotten that before the move we had to change some failed
disks (typical "i'm going away from this old platform so i wont pay
maintenance").
Before the move i replaced both disks but with such a tremendous amount of
luck that during the rebuilding process the system went down due to a
misplaced foot (dammed 520 without redundant PSU and damm datacenter with
all the flooring removed)
Today i attempted to bring it back to life but it kept crying about dirty
cache. So off i went into DST (from CD of course), recovered IOA cache and
tried again but neither the original disk nor the replacement wanted
anything to do with IPLing.
I'm waiting for the client to bring what is supposed to be an op21 but in
the meantime. There is no way to re-replace said LS disk is it? I remember
Dr Franken saying that once it's down it's down for good.
What's weird is that this machine (with the LS drive damaged) was doing
IPLs without problem (it blew an ACModule on it's 5074) but only when
shutdown while rebuilding did it damage the array beyond repair...
In any case, i've got a while before starting the recovery, if anyone has
an idea, i'm open to them.

Best Regards,

Roberto