The “LO” display simply means your infrared sauna has not reached 90 degrees yet. Once your infrared sauna reaches 90 degrees F, it will start to display actual numbers.
The colder the environment the sauna is in, the longer the warm-up time will take. This means the “LO” will read on your screen for longer if you’re in a colder environment or possibly on a patio. If your sauna is in a heated environment, the sauna will not read “LO” for that long. If your sauna is stuck on “LO” after 30 mins, then try unplugging your sauna from the wall. Let it sit for 10 minutes, and then plug it back into the wall. This will reset your control panel, and the sauna should be working just fine.