Tall freezer not working

I have a matsui mtf1857s large upright freezer which is about 5 years old.I keep it in the garage and over the years it built up large amounts of ice and frost on the top shelves.I also noticed my wife accidently has left the door open more than a few times.Anyhoo it eventually started making a strange loudish humming noise and some of the food was soogy inside so we had to remove it all and I let it defrost for a couple of days.When I plugged it back in the compressor is working(can hear it and feel it)but getting very warm but the freezer itself isnt getting cold at all.I cant see or smell any coolant leak.I realise its probably not worth repairing (its a currys special!!)I know its been abused but i just wondered what the fault might be.Also are there any fans on these types of freezer?Cant see one.Also our next freezer might be a chest one and i wondered if these are more suitable for garages