@edmondshnaider from a hardware perspective, BT and WiFi are pretty much the same circuit on the IC. Use the Samsung Troubleshooting page for the no BT/WiFi issue
[image|3599074]
That means you will need to check the components as listed on the flowchart (i.e. C3014 etc.) Use your PDF readers search function on this [document|41554] file, to locate the components on your boards. Ones you find if there are components that are failing, let us know which ones so we can try to find the proper replacements for you.
Of course, you want to make sure that you have your software updated (if available ) and that you checked the network settings. Sometimes a reset might resolve this as well, if it is firmware/software related. Just remember that a hard reset (factory reset) deletes all settings, 3rd-party apps, app data, and media and document files. Make sure you have your phone backed-up before trying this.