Do you mean freezer was jam packed and sealed with ice?
I did ours the other night - switch whole appliance off. Open the fridge as little as possible and the stuf will stay very cold, and you could put some of the freezer stuff in there too while you defrost it and they will keep it cold too.
When you can get the drawers out of the freezer, put a washing up bowl with water from a boiled kettle on the shelves and the ice will melt faster. Very satisfying!
When i lived with a mate we tended to leave it on, and the hammer at the ice with knives and also hair dryers, although don't tell my mum she'd kill me if she knew that, we also use to wear gloves, but so satisfying when a big bit of ice broke off
DO NOT use knives! I did that while staying at a friend's house as a 'helpful' thing to do for letting me stay. I managed to stick a knife through where the gas is that keeps the freezer cold (or something), and he had to buy a new one. Not only that, he told me to open the windows and wait for him to come home - which I did, and then the wind caught the windows and slammed them, smashing them too.
The best way to defrost a freezer , if you have a tumble dryer , is to put the hose into the freezer , seal as best as possible and turn on the dryer . 20 minutes at the most to defrost a very icy freezer