Any of us would need a lot more information, and pictures, in order to try and guess what may have caused your issues.
What type of roof? Rubber, TPO, etc.
What climate? Has the roof been subjected to extreme heat and cold? Vinyl flooring has been known to shrink and crack in extreme cold weather. Maybe tired roofing material can do the same. It is 10 years old. That's a lot of sun, wind, water, maybe freezing.
What kinds of wildlife may be around? Squirrels and Chipmunks are known to dig and scratch, trying to find a way in.
When you replaced the lap sealant, did you maybe use any cleaning chemicals that may have damaged the roofing materials?
Pictures would really help in getting suggestions for repair.