Vent: my walk in cooler died at 9pm on a Friday with $2,400 of product inside

So the compressor on our walk in just quit around 9pm on a Friday, right in the middle of a full dinner rush with 80 covers still on the books. I walked back to grab the butter and it was already at 55 degrees, and the digital gauge was climbing a degree every few minutes. We loaded what we could into the reach ins and two borrowed coolers from the bar next door, but I still lost about $2,400 in fish, dry aged steaks, and all my house made stock. The repair guy could not get there until Saturday at 7am, so we spent the night rotating ice bags like idiots. Now I am trying to figure out if a cheap temp alarm is enough or if I need a real monitoring system. What do you all run to catch this before the product is already gone?