DS18B20 temp sensor read 85 C

There is a footnote on page 4 which says "The power-on reset value of the temperature register is +85°C."
so if you read 85 degrees it means it hasn't done a conversion since the last power on.
You hadn't wired it up properly so the sensor was being powered off and on periodically, which resets the register to 85 and that is why you got a valid CRC from it.

Pete