Recover a board from corrosion damages
Circuit boards can often be cleaned with Isopropyl Alcohol (also referred to as Isopropanol or IPA, easily purchasable from most online vendors or a local pharmacy in the first aid section).  I use a tooth brush for gently scrubbing corrosion off of PCB surfaces and allowing the board to dry completely before trying to power it on again. That said, the damage looks fairly severe and it's unclear whether cleaning alone will recover the board's normal functions.

Example: https://www.amazon.com/Swan-M314-Isopropyl-Alcohol-99/dp/B00NMPLSZ6/ref=sr_1_12?keywords=Isopropanol&amp;qid=1573709322&amp;sr=8-12