Um, I don't think the 7248 has a LED display, or a service processor, or is supported by the diag cd / program, even SMS is not on-board and has to be loaded from a diskette.
The "Problem Solving and Troubleshooting in AIX 5L" gives them a brief mention.
http://www.redbooks.ibm.com/redbooks/pdfs/sg245496.pdf
In recent years, the RS/6000 family has migrated to Peripheral Component
Interconnect (PCI) bus technology. Throughout the rest of this redbook,
machines of this type are referred to as PCI machines. Initial machines of this
type (7040 and 7248) did not have the three digit LED or three position key mode
switch of the previous MCA machines.
There are two RS/6000 models that do not have the capability to run AIX-based
diagnostics. These machines are 7020-40P and 7248-43P. To run diagnostics
on these models, you must have the SMS diskette for the machine.
In the 7020 and 7248
machine types, SMS is very important, because it is the only way of
diagnostically testing the machine due to the fact that AIX diagnostics are not
supported. On these two machines, SMS is loaded from the SMS diskette.
As previously mentioned in this chapter, there are two types of machines on
which it is not possible to run any form of AIX diagnostics. These machines are
7020-40P and 7248-43P.
The only method by which hardware tests can be run is by using the SMS
diskette that was shipped with the machine.
etc. etc.
So where can one get one of these "SMS diskettes that was shipped with the machine"?
If your boss does not have one then it looks like we stumble onward in the dark because I bet you cannot download a copy from IBM anymore, if you ever could.
Have you tried fsck to check for and possibly repair any damaged filesystems?
Sticking the drive in another system may well be your best bet.