Acktually, this is a decent last resort if you have an alkaline battery leak all over a PCB. Hot water is probably not a good idea as you run the risk of warping a board.

A tooth brush and an isopropyl bath is probably a better option unless you have a good ultrasonic cleaner.

An isopropyl bath after a water bath is also good as to remove all the water from places you can’t dry easily. (Evaporation of the IPA is hella better than using a hair dryer because again, warping.)