According to this site: http://web.mit.edu/3.082/www/team3_s02/materials.html Potassium Hydroxide is the electrolyte for NiMh batteries. It is some very seriously toxic stuff. There is a link on that site to the MSDS for Potassium Hydroxide which will tell you what the dangers are and possibly some things you should do for cleaning up. In the meantime, stay away from the room with the residue until you're sure you've got it cleaned up. Sorry for the bad news. I hope Spektrum accepts the responsibility for this. Glad you're OK.