Could my MacBook Pro screen be broken even if I can't feel a crack?

A display can be damaged internally even when the outer surface feels smooth. Based on your description, a screen fault is possible, but it needs an inspection to confirm what failed and whether the display needs replacing.

Contact Apple or a qualified repair shop for a diagnosis and an estimate. Check your warranty or any coverage you have before agreeing to a repair.

One possibility is that something small got caught between the screen and keyboard when the lid closed. That can damage a display without leaving an obvious crack you can feel, though it isn't proof that's what happened here.

If you can, connect it to an external monitor. A normal picture there would suggest the problem is with the built-in display or its connection, rather than everything the computer is sending to the screen. It won't pinpoint the failed part, though.