After dis assambling Samsung GT-S5830i chek mother board if there is any carbon water damage or rust.clean whole board with electronics cleaner and then apply hot air for a few mints so that it can be dry.
Replae led if it is a jack lcd and if it is pasted then after removing check its prints value.if value is ok then replae lcd and if alue is missing then check whole parts componenets as iven in above diagram.check all paths and if any tracks of them is missing apply jumpers.
It will help you to solve Samsung S5830i LCD Display Light IC Solution Jumper Problem Ways
Samsung Galaxy Ace S5830i LCD Display Light IC Solution Jumper Problem Ways LCD Display Light Not Working
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