I did PU injection for my car porch at 2k and toilet for 3k. So far already a year, no leaks.

Minor cracks can use PU injection and no need to hack anything.

In fact, during the process, the PU actually exited from the toilet to the living hall at few spots. It is also the same for the car porch where the PU exited from several spots.

Once done, apply 2-3 layers of silicone based water proofing and let it cure for 24 hours. Once done, whatever it rains, the water will just gather at one spot and dissipates. Previously, it would have seeped through and leaked below.