As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURN BACK: NR 1 INU RED WARNING LIGHT ILLUMINATED AFTER TAKEOFF, CDU SCREEN BLANKED, CAPTAINS HEADING AND ATTITUDE FLAGS IN VIEW. F/O ADI ATT FLAG CAME INTO VIEW BUT F/O ADI WORKED PROPERLY. F/O FLAG RETRACTED AFTER 5 MIN. REPLACED NR 1 INU PER AMM 34-41-03 AND UPDATE NAV DATA BASE OPS CHECKED OK.