One of the readers, Norm asked, “Do you know where I can find the tweak to enable the camera flash even at low battery levels?” That’s a good question. By default, HTC HD2 camera flash is disabled when battery level drop below 20%. You cannot use camera flash on either photo or video mode. So how to enable HTC HD2 camera flash on low battery?
By changing the registry will do the trick.
HKEY_LOCAL_MACHINE\Drivers\BuiltIn\Battery\
- FlashLightPowerUnavailable value from 1 to 0
Just in case you need it. Here is the link to Free Windows Mobile Registry Editor. Note – this is not a permanent solution. You need to change the registry again after you soft reset your phone. 
via: xda-developers
Tags: 6.5, Battery, camera, flash, HD2, HTC, HTC HD2, low, registry editor, T-Mobile, Windows Mobile, xda-developers
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Wow, this is pretty cool. Will be helpful to all HTC users
Hey, I was the one who made the thread with this solution, which didn’t work out for me. I actually just ended up deleting that registry entry and it works perfectly. I can take pictures with flash at all times. Thanks!
Thank you, Norm.