My sister asked me to fix their roof which keeps on leaking even after it was re patched by some construction workers. Here are some of the things we found out in repairing seals on your roof
a certain area was evidently a trouble spot since it shows signs of accumulated rust and layers upon layers of seal and waterproofing (the original asphalt, the one painted green, and the recent gray.) seeing cracks within the seals, we decided t0 remove all the seals.
as we suspected, pockets of moisture and water lies under all those seals. Although there are layers of seals, some had succumed to time and heat which led to cracks within the layers. We decided to peel off all the layers of sealant.
the shotty way this overlap in the flashing is sealed makes the perfect spot for a 'capillary effect', wherein the small creek opening up to a larger interior space creates a vacuum therefore siphoning the water into the larger interior space. You have to make sure this area is sealed up good.
another example at the junction between the flashing and the firewall which needs to be sealed up