[1] The backlight behaves oddly in combination with the bootup password. I've noticed that when the PSR-500's backlight is in "Normal" mode, the LED comes on when the radio boots to prompt you for a password, but it goes off as soon as you start entering the password. This has been reported here before, but still needs fixed: I.e., the backlight needs to stay on until the password is entered.
[2] I found another bug this week. After the latest firmware, if your PSR-500 is in "Stealth" mode for the backlighting, and the radio is set to prompt for a bootup password, the LED comes on to enter the password (arguably, a violation of the Stealth-mode setting), and never goes off. Since the LED button is disabled in Stealth mode, there isn't even a way to turn it off manually. Your only choice is to go back to Normal mode, turn it off, and then go back to Stealth mode.
...R
[2] I found another bug this week. After the latest firmware, if your PSR-500 is in "Stealth" mode for the backlighting, and the radio is set to prompt for a bootup password, the LED comes on to enter the password (arguably, a violation of the Stealth-mode setting), and never goes off. Since the LED button is disabled in Stealth mode, there isn't even a way to turn it off manually. Your only choice is to go back to Normal mode, turn it off, and then go back to Stealth mode.
...R