Playstation controller will not connect - Flashes blue

Hi all,
I recently took my perfectly fine working PS4 controller round to my friends for bit of 4 player Fifa
However when trying to re-connect back to my system it just flashes blue and fails to switch on or do anything else!!
I have tried resetting the pad however that doesn't work - Any ideas?

Assume you’ve connected it to the PS4 via it’s charging cable?

Indeed - Still flashes Bue

I did go round to said friends house to try and disconnect from his system but made no difference

I had this exact issue not long ago. Turned out it was because the USB cable wasn't original / manufactured by a third party (worked fine for charging but not syncing to the PS4 for some reason).

I had a few original PS4 controllers and the original Sony charging lead, I sold one controller on eBay and the guy got back to me said it wasn’t syncing and was flashing blue. It was working perfectly when it left, I though wtf is he lying or something. So I looked into it and found it might be due to the cable, or it might just need resetting as their a reset button on the back, I tried that but still didn’t work, I also found out that the controller might need an update, but I didn’t look further into that bit.

Tommo. said:

I had this exact issue not long ago. Turned out it was because the USB cable wasn't original / manufactured by a third party (worked fine for charging but not syncing to the PS4 for some reason).

Click to expand...

This could be the reason. I recently purchased a cheapo cable from eBay as lost the original

Tommo. said:

I had this exact issue not long ago. Turned out it was because the USB cable wasn't original / manufactured by a third party (worked fine for charging but not syncing to the PS4 for some reason).

Click to expand...

This worked. Thank you sir