User Manual

8. Tighten the screws to secure the base cover assembly.
9. Turn the computer over and reinstall the nano-SIM-card tray if you have removed it.
10. Connect the ac power adapter and all disconnected cables to the computer.
Troubleshooting
If the computer does not start up after you reinstall the base cover assembly, disconnect the ac power
adapter and then reconnect it to the computer.
Memory module (for selected models)
Prerequisite
Before you start, read Appendix A “Important safety information” on page 85 and print the following
instructions.
Attention: Do not touch the contact edge of the memory module. Otherwise, the memory module might get
damaged.
Replacement procedure
To replace a memory module, do the following:
1. Disable the built-in battery. See “Disable Fast Startup and the built-in battery” on page 51.
2. Turn off the computer and disconnect the computer from ac power and all connected cables. Then,
close the computer display.
3. Remove the base cover assembly. See “Base cover assembly (for T490 and P43s only)” on page 52 or
“Base cover assembly (for T590 and P53s only)” on page 54.
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T490, T590, P43s, and P53s User Guide