You definitely want to follow the manual procedure to avoid a possible load loss:
9.1.4 Transfer from Normal to Bypass Mode
To transfer the critical load to Bypass mode:
C A U T I O N
In Bypass mode, the critical load is not protected from commercial power interruptions and abnormalities.
Press the CONTROLS
pushbutton on the main menu bar. The System Controls
Press the BYPASS
pushbutton on the System Controls menu bar.
The UPS transfers to Bypass mode and the critical load is immediately supplied
by the bypass source. If the bypass source is not available, the power processor
remains on and an alarm sounds.
The UPS is now operating in Bypass mode and the BYPASS
status indicator is
The power module (PM) status indicates READY. The system is now on bypass
and the UPS power processor remains on.
At this point, you can operate an external bypass switch to get to maintenance bypass if needed.