Submerge the logic board in isopropyl alcohol, and allow it to soak long enough to loosen hardened residue, and to displace any remaining water or other liquid. Use a soft brush to remove visible corrosion and residue.

Residue from motherboard left in isopropyl alcohol container.

Clean all flex ends, battery contacts, connectors, chips, and fuses on motherboard with a soft brush.

Repeat cleaning if necessary, or if traces of residue are still visible.

Allow the logic board or other parts to dry completely before reassembly.