No light for both filters

The instrument Multiskan EX plate reader has just been moved from the second to the first floor. After that, on turning it on, there was a notification of "No light" for both filters 450nm and 650nm and it could not read the plate.

Would you help me to figure out the trouble shooting for this or/and share with me its "User manual", please. 

Thank you a lot.

Nguyen Thi Thuong,

Hepatitis lab. 

National Institute of Hygiene and Epidemiology (NIHE),

Hanoi, Vietnam.