If your 45i turns off on its own:

The 45i has an option to use a timer. Do you have the 2-hour, 4-hour, or 12-hour option selected?

How to use the timer:

1. Ensure the LOCK button is not being used. If it is, press and hold the LOCK button for 3 seconds to unlock the control panel.
2. Press TIMER to have the air purifier run for a set number of hours (either two, four, or twelve) before turning off. Once one of the three options are selected the light below the selected hour will appear.

Note: If none of the preset hours are not selected, the purifier will continue to run until you manually turn it off.

If the lock and timer are not the issue, perform the following steps. 

1. Unplug the purifier from the wall outlet.
2. Remove the panel and the filter from the purifier.
3. Let the purifier rest for 30 seconds without the filter or panel installed.
4. Reinstall the filter, making sure that it is placed securely back in the unit (insert bottom of the filter first, and then press the top in until it clicks. Then proceed to press on all four corners to ensure that it is completely locked in place.)
5. Place the panel back on the unit, making sure it closes tightly.
6. Plug the purifier back into the wall.
7. Press the power button to power on the purifier.

The customer may need some time to see if the issue is still happening. Give them that time and have them reach back out if they're still experiencing the issue, so you can follow the Warranty steps.