Replaced screen stopped working

A couple days ago, I succesfully replaced the screen of my device. Everything went OK until now. Now, the touch works, there is backlight, but the screen doesn't show any image, it stays black. Is this because the replacement was bad, or is it fixable? The phone has not suffered any damage.

I already made sure the flex was correctly attached, I also booted without the flex and the backlight disappeared, so I think that is not the problem