Best way to get rid of smell in a used freezer is? What

The drip pan on any freezer collects ice melts from the evaporator during the defrost cycle. Most of them are mounted on the compressor and use the compressor waste heat to evaporate the water.
If there is rotten meat smell in the drip pan it means there is also rotten meat smell in the evaporator coils and fins.
It's almost impossible to get "stuff" out of the evaporator fins unless you take the unit apart.
This means you will probably have to remove and replace the refrigerant plus evaporator and the entire process could take two 8 hour days or more.
Alternately,
after you completely wash it out you can try placing a pan of hot water in it and run it empty. The steam will condense on the evaporator and freeze. Then defrost it . Hopefully this will wash some of the funk away. You might have to do this several times.
If that doesn't work then cost wise the unit is junk.
Suggest in future wrap your meats in freezer bags or other
water/air tight containers in case power goes off.
Monitoring your freezer is a must to catch issues before smelly spoilage can set in.

Have it clean and use a appliance cleaner that has fragrance to smell it good again.
You must eliminate the source of horrible smell.
Then apply the cleaner on rags, wipe it around the freezer exterior.
Some freezer do have pan and some don't have, so you should look for it carefully.
Good luck.

well when i used to have to climb into super market freezers and defrost we used water from the tap it doesn't have to be hot so i would take freezer outside to do this as it might not be drained and if it does have a drain it would only take a minute amount of water which an element would heat up and burn off so empty freezer take outside wash out with water till all gone and to get rid of any smells was out with vanilla essence all fridgies i know and myself used this as it will clean out fridge smells, you then replace freezer back once all water has dried off especially electrical try not to get wet but if you can't help it, it won't matter just let dry or blow out with air compressor then replace freezer back to where come from run freezer for a while till temperature drops below zero then start to restock the more you put in it the longer it'll take to freeze, so just do little by little hopefully this has helped but its usually the only way to do this

use a strong solution of clorine bleach(in a spray bottle) to get into every nook and cranny/drainholes/drip trays/door seals and wipe dry(clorine is a gas and will dissipate within an hour or so)then wipe over interior with a damp cloth and plenty of bicarb,leave to dry and leave any bicarb residual inside fridge as this will absorb any smells left.leave door open for about a day in a warm (ish) room, this is the only way of deoderising......

I have found that the best cleaners for removing left over odors are citrus based cleaners. They help to neutralize odors and prevent re-occurrence. You could also use a diluted bleach as well to sanitize the inside. Make sure it is not too potent or the bleach odor will overcome the bad odor in annoyance.
Good luck!!

the ice cream is the clue,if it goes hard then the temp is too low (ice cream best kept at -18C)
either the defrost is not working or interior temp sensor duff.

that is because when you want a colder unit the sensor is detecting a warmer interior hence red warning light comes on.leave it at the setting you want and within 24 hours the red light will go off.
strongly recc you use a freezer temp gauge so you dont get rock hard ice cream(-18C is best)

switch off,with door open let it defrost naturally...if you have time dry out as best you can and using bicarb wipeout interior(dries and deoderises.then tape up door to stop it opening in transit.

Your problem could be caused by a clogged drainage tube. even though you may have removed the ice it may still have a clog. my suggestion would be to take all of the contents out of your fridge and let it sit unplugged for atleast 24-48 hours with the doors open this will eliminate any left over ice that may be clogging your drain tube. if this dosent help then you may have a defrost heater problem, or possibly a defrost termination switch problem. as for the smell i know that vinegar works well for getting rid of odor. ther eis also a product you can purchase called fridge aid, it is a charcoal based air purifier and should work well.

There is a curing process for the foam used to insulate these. It can give off a pungent odor until it is fully cured. Only experienced it a couple times in the last 20 years. eric