AAA battery leaked all over my TV remote control. Poisonous or just nasty?

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.

@dabbler – thanks – I haven’t had a leaking battery for dozens of years. I remember when I was a kid my dad said “don’t touch it” when a battery leaked, but what do kids know?

Dude…it’s acid! Yes, it can hurt you and anything it comes in contact with.

I use baking soda and water to clean the acid off of corroded car battery posts. Don’t know if it will work in this case, but you might try. Keep water away from the contact point inside.

Wear plastic gloves.

In general – depending on the battery type! there are so many more now than when we were younger – what leaks out from most “consumer type” alkaline batteries is slightly toxic and highly corrosive. It’s corrosiveness is what caused it to leak from an imperfect seal in the first place.

If you have found the leak in time then you may be able to save the equipment with a good cleaning. That involves thorough wiping of the corrosive material, some rinsing (if possible) and wiping / drying to be sure that it’s all removed (and the moisture that you introduce in cleaning is also removed!) so that the corrosiveness is cleaned and neutralized.

If you don’t find it in time, then you’re stuck with a component / item with frozen-in-place leaking batteries that may not even be removable through normal means.

A Ni-Cad (Nickel-Cadmium) batter is much more toxic.

This is the 21st century. The chemicals used in alkaline batteries are nowhere near as dangerous as in the old days with acids. That is why they can be safely disposed of in the trash. They are slightly corrosive but not to the degree of the early batteries.
Hold the remote so the battery opening is facing down and clean off the crud with a toothpick. After you have removed most of it, use a damp rag or Q-tip to wipe the terminals and clean out the area.
Don’t use the cheap batteries that are usually packaged with remotes made in china. They are junk.

LuckyGuy has the proper approach. Energizer says this: Ingestion: Swallowing a battery can be harmful. Contents of an open battery can cause serious chemical burns of mouth, esophagus, and
gastrointestinal tract.
Inhalation: Contents of an open battery can cause respiratory irritation.
Skin Contact: Contents of an open battery can cause skin irritation and/or chemical burns.
Eye Contact: Contents of an open battery can cause severe irritation and chemical burns

Clean up carefully, dry everything and hope the corrosion didn’t ruin the remote.

Most modern batteries are alkaline; the opposite of acid. They will still burn you, but @Dutchess_III has precisely the wrong idea on how to handle it. Good thinking, but wrong. You neutralize acids with a base, and since car batteries are still lead-acid like the old AA/C/D-cells, that works for car batteries, but vinegar (an acid) is better for neutralizing the base of a leaky alkaline cell.

OK. I stand kerrected. Let us know if you blow up!

I use the same approach as @LuckyGuy

Poisonous and nasty. Clean it up and neutralize the acid with some dish detergent. Spray on lightly, then wipe off thoroughly. If anyone in the house is handy with small screwdrivers and electronic devices, they can take it apart and clean it for you. A TV repair shop can do it also.

cleaned it, but apparently the corrosion damaged something inside.

Thanks for all the advice. I’ll need a new remote.

No!!! Don’t give up yet! Please!

Was the remote sitting in its normal position of use – on a surface with the buttons up? >90% of them are designed correctly to have the batteries drain away from the circuit board.
Just make sure the contacts are clean. Try cleaning it with rubbing alcohol If one contact is gone solder a new one in place or fold up a piece of aluminum foil to make one.

Promise me you will spend at least 5 more minutes on this project.
If you fix it, you just paid yourself $240 per hour. (Assuming a remote is $20.)

. .

@LuckyGuy – yes, it was sitting “normally”. I don’t have any rubbing alcohol in the house but I’ll pick some up this morning, I’ll let you know it goes.

I need a bumper sticker: “SAVE THE REMOTE!”

I’ve got to know….
Were you able to save the remote? Or did you use this event as an excuse to justify the purchase of a new TV?