I just received an official refurbished Osmo 3 from in sealed box today and it wouldn't power on. I put it on charge and while the charge cable was plugged in it would work perfectly fine in all operations except that the LED remained red while the white LEDs flashed in sequence. When I unplug the charge cable it immediately turns off. Reading the manual, it states that a solid red LED indicates the battery is over-discharged so when I arrived home I put it on charge with a power adapter matching the recommendations (10w, 2.1a, 5V) and left it to charge. It seemed to be going well with first one blinking white LED, then cycling through 2 and finally 3. Despite the manual stating it takes around 2.5 hours to charge, the white LEDs didn't didn't stop cycling for nearly 5 hours.  

So thinking it was fully charged I unplugged the device and it would not power on at all. No response to a long press or even a short press, which I read gives you a battery indication reading instead of turning on. No lights came on at all. So I plugged it back into the charger and it's back to one white LED flashing. I turned it on while still plugged in and the LED that was once solid red is now solid green. While it was on I followed a tip I have seen recommended for many issues both similar (though not quite the same) and otherwise by holding down the trigger, shutter and power buttons for 30 seconds. I then powered off the device and unplugged it and tried powering it on again. Now I get a response but not one I was hoping for. The device now has a rapidly flashing red LED everytime time I touch the power button, regardless of long or short press.

One other thing to note is that the device emits a high pitched ringing noise which is slightly rhythmic while it is charging. I confirmed that it is the device making the noise and not the power adapter by putting my ear next to both. The device doesn't have any noticeable change in temperature when you touch it and it seems to be charging according to how the manual describes so I'm not sure if this is something worth worrying about? The noise stops immediately after unplugging the device as well.

Is all this normal behaviour, considering the battery was dead on arrival or should I consider excercising the warranty on this?

UPDATE: when I woke up this morning there has been no change and there is only one white LED flashing despite being on charge for around 9 more hours. The device still only works while plugged in and immediately shuts down when it’s unplugged. Pairing it with my phone through the DJI MIMO app it tells me the battery has only 20% remaining despite all the charging it’s had and when I try to power it on Without the charge cable plugged in I still only get the flashing red LED. I’ve started the warranty claim process through the seller this morning as there is an obvious issue with power delivery from the battery

Hello there ero_senin05. I am sorry for the trouble this has caused and thank you for reaching out. Since we are having this issue with your new DJI Osmo Mobile 3, I would recommend for you to contact our DJI Support Team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. We will do there best to help you and give out the best resolution for the said issue. Again I am sorry for this trouble and thank you.

UPDATE: Support says I need to send the gimbal back for diagnosis