answer:Yes, it’s poisonous and nasty both. But if you are careful about it, I think you can deal with it. [ disclaimer: I am not a professional hazardous waste handler, proceed at your own risk. ] I’ve something like the following many times… Be prepared to throw away or thoroughly wash whatever comes in contact with the leakage. That stuff is poisonous if you consume it, and might get into you from prolonged contact, so just minimize contact. Paper towels are your friend in this situation. Also dig up an old decommissioned toothbrush if you can. Lay out a paper towel to work on and open the thing up over it. Use the toothbrush to gently scrape out the gunk from the inside of the remote. Use a couple damp paper towels to wipe out the battery compartment. Use the toothbrush to clean off the battery contacts. On each there should be a least a bit of shiny/non-corroded part available to contact the battery. Let the thing dry out completely before you put batteries back into it, and throw out all the paper towels and wash your hands thoroughly. Either throw out the toothbrush or wash it thoroughly.