This one has an electric solenoid on it.

Is it possible to gain access to the brake by removing the battery pack? I really don't have a safe means of lifting the truck enough to get under it and work..

I located the brake hub and a manual release lever under the floor pan. Everything under the truck looks nice. Seems every few times the brake actuates, it pulls the manual release handle down and pulling it will free the brake for another few cycles. So something is certainly loose or binding. When it doesn't release I can hear th solenoid trying to move but it can't.