After replacing LCD screen and Display FPC connector, black screen

Hi everyone.

My sons switch got broken, I had to do a mid frame and LCD screen replacement.

While I was installing the new LCD, I have realised that the FPC connector for the ribbon cable was damaged and replaced it.

Although I have replaced the connector and the LCD screen, I get no back light, the screen is off, nothing happens.

What could be the issue and how can I check it?

The only thing I thought might be the issue is that maybe I soldered the FPC connector not well, but I am unsure if that means anything regarding the back light as well.

Also, the console work well, while docked, but no screen.

Thank you for the reply.