Have arranged to return the battery for another unit. 
I had ordered a replacement OEM 56Wh battery for a XPS 15 9550. With the replacement battery installed, the system sees the battery as a non-Dell battery and will not charge. The laptop will however run on the battery when the AC adapter is unplugged. Have tried various options to reset the BIOS and CMOS, short of removing the RTC battery; due to the amount of disassembly required, without success. I've tried keeping the power button depressed for 30secs which a few posts have suggested. No luck. Can anyone recommend any steps to take that are likely to resolve this issue? The reason for replacing the battery is that it did not hold charge for long after the AC adapter is removed. Also, system diagnostics was reporting that the battery had reached it's serviceable life and should be replaced. The same message regarding the battery health was presented when running diagnostics with the new battery installed. Another symptom while the new battery is installed is the front light flashing between white and amber. Having reinstalled the original battery, I can confirm that this battery is still recognized as OEM and does charge. Obviously still does not hold charge for any significant time. 
XPS 15 9550 battery not recognized as OEM