Hi, I'm Nathan.Sorry to hear that you're having trouble with this but I'll do my best to help you.
That is the encoder strip, and must be in place for the carriage/printhead to sense its position.
It should be an easy fix though, unless it is physically cut or broken, it just gets stretched back to the opposite side and fits into a little slot in the casing, it should be quite taut when in place.
Well it runs from one side to the other, so if one side is in place, it goes into the opposite side. It should be pulled tight from left to right all the way across the back.
The lid really only lifts up in the are to replace the inks. It may help to take a flashlight to look inside more closely though