Samsung Galaxy S4 — Can not activate bluetooth

Here's the scoop... I bought my GS4 from eBay with a broken screen so i bought a new screen assembly and replaced the whole top portion of the phone. On the first boot i reset the phone back to factory defaults, going through all the normal steps on setup with no problem. After a few weeks of using the phone i needed to enable the bluetooth, all to my surprise the radio button would not turn green indicating it was operational, instead the button stayed greyed out. My WiFi works... a little weak, but it works! i have read a lot on "possibilities that might fix my issue", none of which work i.e. clean contacts with alcohol, replace WiFi antenna etc...
It drives me crazy knowing that my bluetooth can not be enabled, if somebody knows or has had the same issue could you please lend a hand.

Thanks in Advance
Chris

It's a used phone, how do I enter safe mode to see if Bluetooth is working?