So for a while my volume was messed up, it was whisper quiet and that was very unsatisfactory and I couldn't fix it with reseting/turning on and off/looking for options/vol boosting apps.
 
I think the problem starts when you hook up to your car stereo, it's like it goes in a different volume mode or something.
 
How did I fix it?
 
Turn the sound all the way down with the volume button, until the line crosses through the speaker and it's just off.  Now turn the tablet off completely, wait a minute, then turn it back on.  The sound will still be off, but when you turn it back up this time it will be normal.

Awesome.

slybunda
hmm may be in that headphones low power mode to not bust your ear drums?

 
I believe that's part of it.  It doesn't seem to come out of the low power mode when you take it out of headphone/hdmi mode.  My posted fix solves the problem though, a reset doesn't work, you gotta wait a minute or two before you turn it back on if you want the volume to return to normal.
 
And I'm dealing with a power button that may quit working all together right now I have to press a pin in the under side of the power button to turn the screen on/off.  A real pain in the ass but I can handle that, as long as it keeps working at least that much.  I've been super careful with this one and it's still giving me issues.  I wonder if the HP version exhibits the same issues?  I would think it's simply our TN7 with an HP badge on it, though, not a different product.