Daling with Mouse damage? (Not the computer kind)

Just took in a Superbrain-QD which was "stored" uncovered in a garage for the past 10 (or more) years ... It's got serious mouse damage - underneath and all around the monitor was stuffed with insulation, wood chips and bits - obviously a large nest. More seriously, both the main PCB and the power supply PCB are *COVERED* in mouse droppings, and *SOAKED* in mouse urine (mostly dried up now, but the damage has been done). Lots of corrosion and such, but it looks repairable.... But both boards are covered in a layer of dried urine, sprinkled with generous gobs of urine soaked manure (about the consistancy of fairly dry tar), which is "glued" to the board. This is the worst case of mouse damage I have seen ... I would very much appreciate any tips that can be offered on how best to clean the boards without damaging them... ??? Regards, Dave