The warning message is rubbish ... the cell is not broken - or it would show zero !!
What you have is a 'weak cell' ... its not able to handle the power draw and its voltage sags more than the others.
If the battery is still in warranty - the best is to get it swapped out by dealer for a new one ...
But if out of warranty ... then :
Some will tell you to 'Deep Discharge' the battery to about 3V per cell and then charge up fully again ... you can try ... but even if you get it to come up to the other 3 cells - its only a temporary measure as it will drop again literally first use. You can buy adaptors to discharge these batterys to 15.4V storage or switch to 12V deep discharge ...
Battery Control USB Light Charger Power Discharger Adapter For DJI Phantom 3 | eBay
LiPo's are not recoverable ... once they start to fail - its a slippery slope and accumulative. some claim to fix them ... but in all honesty - something else was wrong and they were lucky.
What I would try first ... is SWITCH ON battery and then connect to charger ... let it charge right up and auto cut-off.
Go do a close in safe flight to draw the battery down ... I honestly do not like static running of these models at all ... camera / gimbal gets hot etc. So best is to do a low level flight close in so you can see whats' happening. You can land at any time if needed. Keep flights short of maybe a minute or so ... land ... check battery numbers ... fly again ... repeat ... to get a good idea of what's happening.
Charge up again with battery Switched ON ...
Repeat short hop flights and reading results.
If nothing else - you will get to understand the limitation of a weak battery ... and be able to fly it accordingly.
You can of course of not under warranty and not trusted for flight - use it for updates / bench working of the model to save using a good battery pack. This is a common practice of many modellers with lipos.
Nigel