Chosen Solution

Hello, I recently changed the back of my iPhone 5C and replaced the digitizer, but now the screen doesn’t fit on the left side, I tried to push it but it wont. When I remove battery it does fit, but with battery is about 2 mm up

It could be a manufacturing defect with the back as these are more than likely all aftermarket backs. I highly doubt it’s fully original unless it’s pulled from a new 5c. I would check to make sure the battery is sitting flush in the phone. When you pry the battery out it can warp and get lumps in it. I’d put the battery on a hard flat surface and use your hands to flatten it out. Dont use excessive force, because you may damage it.