never seen jamming reported in a hkc. I'd check the device signal quality, missed polls etc.
if it thinks its being hammer and its armed it should go into full alarm. But id be doing some tests first. Can you post the relevant log sections from the app?
voltage of a battery doesn't mean its ok. You either need to out some load on it to test its capacity. The reason its reading so high is because its just come off charge
dmz is worst case on most routers?
id say most customers don't care as long as it works.... Trying to explain the reasons why make you the over charging numpty who charged for stuff that wasn't needed