Flashing Red Check Mark on UV Detector

What does the flashing red check mark on the UV detector indicate?  Would it be the monochrometer, power supply, or other problem?  I changed the Deuterium lamp and solvent to HPLC grade water.  The check mark stills flashes red.

Update: “A/Z/ OUT OF RANGE” error is displayed, but THF and HPLC grade water result in the same error.  A second freshly opened bottle of THF also showed the error, too.

Update:  I ended up changing out the lamp, which still showed the error after 72 hours equilibration.  Then, I thoroughly cleaned the monochrometer interior, lubricated the worm drive, cleaned all flow cell parts, and cleaned the fan area (because I was already elbow deep inside).  One or all of these cured the problem. . . for now.

Any advice will be greatly appreciated.