How to add more light to a rotating 3D logo

Hi forum.

I got a 3D rotating logo, its doing a 360 spin. The front side has good light to it, but as the logo keeps on rotating to conclude its frame evoluton, the backside of the logo is too dark, how can I brighten it so the light isnt so dim.

I have included the AE file. 

https://filebin.net/l8i9dfnrrzdrd9om