My UPS Supercomp Magnet 700 automatically turns on when power cord is plug in to a switch and cannot turn off after this

There's no info yet at the main site so I couldn't look at the manual.

What do you mean by plugged into a "switch?"

I see it does have a single power button, though I don't understand why you'd want to use it as then it wouldn't function.

I see only a few options for your issue:
1) Power Button must be held down for a few seconds
2) Power Button is broken
3) Can't power off until it's charged (I doubt this)
 
When the Three PIN power cord is pluged it automatically let the UPS ON (without need of switch ON the UPS). Then when i unplug the three pin power cord, the UPS is in a BACKUP mode and then it cannot turn off from the UPS switch untill the battery charged is use finish...is it clear from you