Chosen Solution
i have a macbook air 820-3437 which was liquid damaged, doa. corrosion was around smc and u7700, reballed smc and it turned on however dim backlight. is u7700 the issue or is there anything else i can check
I’d definitely replace u7700, no wonder it might be the cause of the dim backlight. If you have corrosion in the area maybe there’s some filth stuck under it. If you don’t have a replacement try at least a reheat with quite a bit of no clean flux..touch it a little to confirm solder melting point, if it’s just residues it might get cleaned and kick back in properly.
This could be several things that are wrong. Probably the simplest solution would be checking the make sure all connections to the backlight and keyboard have the rust or calcium build up and if there is clean it using a cleaning brush, but be careful not to damage any connections.
