From the Lucent Manual:
The error code/status display on the processor module or the maintenance screen informs you of problems during or after a forced installation. See Table 4–2 for error codes displayed. Also see the screens following the table for errors displayed on the maintenance console or PC.
The following error conditions can occur only during or immediately after a forced installation. Instructions for recovery follow the description of each error condition.
Code Meaning Action
L Upgrade is in progress No action required.
U Install is in progress No action required.
2 Incorrect memory card type Insert correct memory card and repeat forced installation procedure.
4 Memory card corrupted Insert new memory card and repeat forced installation procedure.
3 Incorrectly inserted or missing memory card Insert memory card correctly and repeat forced installation procedure.
7 Bad processor board Check that memory card is inserted correctly and try installation again. If it fails again, replace the processor module.
9 Unknown Try installation again with a new memory card. If it fails again, contact your technical support organization.