Dell S2421H Simplified Service Manual page 6

Remove the Mylar from the hooks of the bracket
S14
chassis module.
Use a Philips-head screwdriver to remove six screws
for unlocking the circuit board, release all the cables
S15
from the hooks.
(No.1~5 screw size=M3x7.5, Torque=6±0.5kgfxcm;
No. 6 screw size=M4x8, Torque=6±0.5kgfxcm)
5
2
4. Disassembly and Assembly Procedures
3
4
1
6
Remove the interface board and power board from
S16
the bracket chassis module carefully, and disconnect
all the cables.