Error Messages; No-Beep Symptoms; Lcd-Related Symptoms - Lenovo ThinkPad L420 Hardware Maintenance Manual

Error messages

Table 3. Error messages
Symptom or error (beeps, if any)
Bad CRC2. Enter BIOS Setup Utility, and load Setup
defaults.
(two short beeps)
Fan error.
(four short beeps, one long beep)
DRAM is unplugged.
(four short beeps, pause, three short beeps, pause, one
short beep, pause, one short beep)
DRAM is not well plugged.
(seven short beeps, one long beep, four short beeps, one
long beep, one short beep, one long beep, one short
beep, one long beep till forever.)
Operating system not found.
Unauthorized network card is plugged in - Power off and
remove the miniPCI network card.
(two short beeps)
System Configuration Data Read Error
(two short beeps)

No-beep symptoms

Table 4. No-beep symptoms
Symptom or error
No beep, power-on indicator on, LCD blank, and no
POST.
No beep, power-on indicator on, and LCD blank during
POST.
The power-on password prompt appears.
The hard-disk password prompt appears.

LCD-related symptoms

Important: The TFT LCD for the notebook computer contains many thin-film transistors (TFTs). The
presence of a small number of dots that are missing, discolored, or always lighted is characteristic of TFT
LCD technology, but excessive pixel problems can cause viewing concerns.
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Hardware Maintenance Manual
FRU or action, in sequence
Press F1 to enter BIOS Setup Utility. Press F9, and
Enter to load the default setting. Then save the current
setting by pressing F10, and restart the computer.
1. Fan.
2. Thermal grease.
3. System board.
Install the DRAM.
Reinstall the DRAM.
1. Check that the operating system has no failure
and is installed correctly.
2. Enter BIOS Setup Utility and see whether the hard
disk drive is properly identified. If you still see the
same error message, check the boot sequence.
3. Reinstall the hard disk drive.
4. Reinstall the operating system.
Turn off the computer and remove the WAN card.
Press F1 to enter BIOS Setup Utility. Press F9, and
Enter to load the default setting. Then save the current
setting by pressing F10, and restart the computer.
FRU or action, in sequence
1. Make sure that every connector is connected
tightly and correctly.
2. DIMM.
3. System board.
1. Reseat DIMM.
2. System board.
A power-on password or a supervisor password is set.
Type the password and press Enter.
A hard-disk password is set. Type the password and
press Enter.