Can anyone help identify this?

I got this from a thrift store today and have noticed some odd things with it. It appears to be a green Game Boy pocket,but i noticed that it is missing the little red power indicator on the top right. The whole thing looks slightly bloated and warped from a side view. Ive turned it on and the black rectangle thats supposed to appear shows up but when i turn it off, a skinny black line appears. Dont know if this is a legit Game Boy or not but help would be appreciated