My Cobra HD 8000 GPS keeps turning on and off on it's own. What can I do

Contact the manufacturer,they would be the only ones that would have it.

No, you pay for the upgrade through the Dealer or Manufacturer.

It sounds like you might have to do a factory reset. Look it up in your manual or go online for the instructions.

Removing any internal battery can bring about a reset in many devices because the settings are stored in volatile, i.e. circuitry requiring a current to store data. When battery is removed the data is lost and the device reset.
You may have non volatile ram though, this can be reprogrammed with an eprom/ic programmer if you have the original file.

Did the freeze come about as the result of a firmware upgrade?

Use your Computer after you plug it in using a USB male type plug,

ask cobra

look up cobra online or local dealer

Question? Did you accidentally hit the sound button on it and mute it? If no then reset the unit and i don't mean power off, i mean use the reset button with a paper clip and try that should bring the sound back on for you and check the volume makes sure it is up.
Hope this helps

ive got a cobra 800 pro hd gps and need a manual .
ive lost mine