Some of us may remember an electrolysis experiment in high school chemistry. An electric current flows between 2 terminals submerged in a salt water solution causing lots of fizzing, erosion and deposition of metals and salts. This is what happens inside your MacBook when it gets wet. However it happens even quicker because the voltages inside are higher and are also at high frequency.
The MacBook would not turn on.
Liquid had contacted the powered components in the top half of the photo. This resulted in electrolysis (aka corrosion) which eroded metals including circuit tracks, solder and damaged electronic components on the logic board.
In this photo electronic components have been removed to reveal the damage underneath them. Here a round metal pad at the centre of the photo has been eaten away including its track that descended into the layered logic board. Finding where the eroded track went inside the logic board is difficult without circuit diagrams (Apple doesn’t release them) but not impossible to someone with experience of circuit design.
This photo shows the components replaced with new and the damaged internal track replaced by a tiny insulated copper wire secured with high temperature resistant UV activated adhesive. The copper wire is 10mm long. This logic board was fully repaired, cleaned of flux residue in an ultrasonic bath, baked dry at 120c, installed in its case and then fully tested before return to the customer. No data lost. No logic board replacement.
