concealed by an access panel that is secured by more than two screws. You must remove the screws
and panel to access the specific CRU. Optional-service CRUs can be removed and installed by users
or, during the warranty period, by a Lenovo service technician.
Before replacing FRUs
Before replacing any FRU, read the following:
• Only certified and trained personnel can service the computer.
• Before replacing an FRU, read the entire section about replacing the part.
• Be extremely careful during writing operations such as copying, saving, or formatting.
The sequence of the drives in the computer that you are servicing might have been altered. If you select
an incorrect drive, data or programs might be overwritten.
• Replace an FRU only with another FRU of the correct model.
When you replace an FRU, ensure that the model of the machine and the FRU part number are correct.
• An FRU should not be replaced because of a single, unreproducible failure.
Single failures can occur for a variety of reasons that have nothing to do with a hardware defect, such as
cosmic radiation, electrostatic discharge, or software errors. Consider replacing an FRU only when a
problem recurs. If you suspect that an FRU is defective, clear the error log and run the test again. If the
error does not recur, do not replace the FRU.
• Only replace a defective FRU.
Locating FRUs (including CRUs)
• Some of the components are optional.
• To replace a component that is not in the list below, contact a Lenovo service technician. For a list of
Lenovo Support phone numbers, go to:
ThinkCentre M720s User Guide and Hardware Maintenance Manual