Freezer warmed up ruined contents at 12°c and then cooled back to - 20

Hi just had an issue with our American style fridge freezer. Noticed a pool of water coming in of night shift this morning opened door everything seemed OK. Went to bed and when I awoke alot of the contents were soggy and spoiled. It got to 12°c Since emptying it and leaving it on as the fridge part was still maintaining its cool temp it's got its self back up to the - 20°c I set it at. I don't really want to fill it again if it's an intermittent fault. The back was dusty so I've cleaned all that. We bought it in around 2015 and in 2019 had it replaced under warranty for the same thing. I can't remember what was wrong with it. With this model it does say 10 year guarantee on the compressor just need to find the paperwork before the Mrs orders a new one. Anyone any ideas?