[Q] Wifi not turning on

I bought a galaxy note n7000 from a friend. It has android 4.1.2 installed. build number is n7000XXLSA.
the problem is wi fi doest turn on.I mean whenever i want to switch it on it seems its trying to get on but fails. The green light never shines on it.
The problem i cant understand lies with hardware or software.
Sometimes the wifi gets connected and then it works like a charm. But most of the times no matter how hard i try it never gets turned on. Ive tried factory reset, restart, removing batter and memory card nothing seems to work. I tried wifi fixer app but nothing happened.
I am not very technically aware of rooting, and how to modify it. But i think from what ive learnt is it is caused by updating from ICS to jelly bean 4.1.2
I dont know whether my phone is locked or unlocked, rooted or un rooted cause im totally new with phone.
Please someone guide me how can i rectify this problem, I dont mind taking risk with my phone but wanna know what all should i do to solve wifi issues.
Plus i also would like to update to 4.2.2 kindly let me know step by step starting from basics how should i go about it.
regards