Samsung Galaxy S5 — tmobile galaxy s5 wifi won't toggle on after lolipop 5.0

please help I am not very good at all this so any bit of detailed help will be better than nothing at all. I downloaded lollipop 5.0 was running KitKat 4.4.2 before.my wifi stopped working shortly after replacing my screen still running 4.4.2 but the research I have done has shown that lollipop 5.0 has some WiFi issues.if I go to settings and to my wifi I try to toggle it on and it switches on but stays grey and does not turn green. sometimes it will just stay grey in the off position and won't even toggle on. it is intermittent. I loaded 5.0 with kies.because I had no wifi whatsoever. thinking it would be just a matter of the update. basically I have a useless Samsung Galaxy s5. I hate it. I have found a couple people with the same problem but no one has came up with a solution. I have tried factory data reset numerous times cache partition every little trick shown on the Internet but still nothing.Can someone please help