READ! TASCAM DR-70D 4-Channel Audio Recording Device for DSLR Cameras - Black. Battery tray does not power the unit on. It had battery corrosion. I cleaned it with 90% rubbing alcohol, but not with the proper connection fluid. The right person could get it functional again. In any case, IT WILL POWER ON USING A USB POWER BANK (micro usb connection), and that is how I have been powering it whenever I’ve used it (even when the battery tray was working). As is/ No guarantees/ no returns. Shipped usps priority.