I have a Harmony 659, and recently the timed shutoff of the glow/backlight stopped working. Once it comes on, it stays on until the batteries are dead. The only way to turn it off is by explicitly pressing the "Glow" button.

After some searching, it appears that this is a fairly common hardware problem that affects multiple models. My Harmony has been used only a few times, so this is definitely a design/quality flaw. The only workaround I can find is to change the Glow Setup to "None" via the Harmony software. In this mode, the backlight only comes on when you explicitly press the Glow button. So this basically gives manual on/off control of the backlight.

Has anybody found a solution for this problem? I would be interested in a DIY fix if possible.

Note that this is NOT the same issue as in the Harmony One. That issue is/was firmware related, while this one seems to be hardware.

Same here on the H360... i'll try setting it to none (ive only tried other times actually) and see if I get the same result.
Ive isolated that it is only problematic when activated using one of the soft/screen buttons, the other buttons turn off properly... however the soft buttons are used for activity so... pretty much used all the time.
Lastly, there seems to be a possibly related glitch where if you do a safe mode firmware update, and put the batteries back in while the remote is still connected to the computer... itll always assume the batteries are almost dead and not turn on the light... this only started at the same time the backlight stopped working properly.