I was checking it out this morning after a few weeks of not using it and noticed it still had 21% battery life left, the OSTC 3 switched itself off as normal while I was looking for new firmware and when I tried to start it again it stayed black. I switched the batteries but apart from a small red light after first install of the new battery no action on the device.
Sorry for the delay in answering, we just returned to the office from the "boot" dive show. Did you get this working again already? If not, please contact us directly for help: info@heinrichsweikamp.com