UP should only be present on startup of a new outdoor unit once all setup is complete.
Trane US stop selling this Equipment in 2018 and went to Mitsubishi VRF .
I'm seeing it come up on older Equipment after it has been commissioned for a number of years.
For Temporary use of the Outdoor unit, you can press and hold the K1 button for 5 seconds, this will start the Commissioning process.
Once Test Complete is shown in the Tool, you can press K3 for reset and it will continue to operate, it will come back again, so the following will need to be done.
I recommend replacing the HUB PCB as a start, I have seen this take care of this.
If the HUB replacement doesn't take care of this and UP comes back the Main PCB with a new Eeprom will have to be installed.
When replacing the Main PCB and Eprom , the firmware will have to be uploaded through the TUT tool or S-NET .
New Eeproms come blank, the Firmware is located in the help center under (https://support.trane.com/hc/en-us/articles/28907670327693-Trane-Branded-Samsung-VRF-Firmware-for-2017-Next-Generation-Products)
After Firmware is uploaded you can press theK4 button 1 time to confirm that the Unit has the correct configuration.