The screen changed: Firmware Update in Progress. Do not power off.
You can find these by searching "PBE-M5-400" on the official downloads portal . How to Update Your PowerBeam M5 400 download firmware ubiquiti powerbeam m5 400
For legacy versions (older than v6.x), check the specific NanoBeam/PowerBeam M5 400 software page0;4c7; . The screen changed: Firmware Update in Progress
If you want, I can: