I'm guessing the difference between the 536 and 436 is this. The 436 runs on batteries with the concern about about battery drain. So there are options on the duration of the backlight's illumination for the 436.
Since the 536 is either AC or vehicle battery, that concern isn't present. However, there are settings for the 536 backlight intensity (Off, Low, Middle, High). There are also settings where you can connect the scanner to a vehicle headlight circuit to change the backlight.
There has been some talk in other forums about the Alert Light (the one around the silver knob). It stays on for a few seconds and some folks have asked if this could be lengthened via firmware update.
May want to check in Sentinel using the profile editor>Display Options. . .