Taking off lens cover

[Yellatang100]

Hey guys, My t5 light hasn’t been working the last couple of days and my coral are dying. I purchased 2 new bulbs today but I cannot get the cover lens off of the light fixture. I have been trying all day to get it off. It looks to be a small Allen key size but I am not sure if I have the right keys. If anyone could get back to me ASAP would be greatly appreciated. Btw this light is 4ft for 90 gallon tank.

 

[Retro Reefer]

What kind of light is it? Pictures? Don’t worry to much your tank can go without lights for many days.