When you’re setting up the password on the Back-UPS HS 500 web interface, don’t put an exclamation mark in the password. If there is an exclamation mark in the password the UPS will lock you out. The unit will be need to be reset and a manual reset through the reset button won’t necessarily fix it.
Although the real source of this problem is unknown or admitted, it is assumed that it must be a firmware issue with the unit. When the exclamation mark is put in the password, it doesn’t register properly and causes the lock out. The firmware on these units is not upgradeable.
Advice: Don’t put an exclamation mark in the password
If you’re stuck and unable to reset the unit through the reset button, call APC tech support and they should be able to give you a back door password over the phone that will reset the login and password. You will need to provide them the unit’s serial number, they will generate a backdoor password and provide you instructions on the reset.
In the USA & Canada, APC Tech support can be reached at: 800-555-2725