Dell 2135cn Service Manual page 607

Chapter 3 Removal and Replacement Procedures (RRPs)
26) Disengage all the connectors of the
PWBA MCU (PL10.7.7) and PWBA
EEPROM (PL10.7.6), pull the harnesses
out from the hole of the CHASSIS MCU
(PL10.7.2).
27) Remove the two screws (silver, 6mm)
that fix the under part of the CHASSIS
MCU.
28) Remove the one screw (silver, 6mm)
that fixes the side part of the CHASSIS
MCU.
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Version 2 2008.03.31