Ice build-up water leak

sheck the back wall of the freezer where it sits in that trough, more often than not this complaint is the fault of a defrost drain. if you can try to remove the back panal on the freezer, if its a defrost issue there willl be a huge amount of ice behind that panal blocking the defrost drain.
after you chip what you can away, you'll find that a hair dryer and hot water are the best way to get that drain clear so it wont happen again