Anyone facing wifi connectivity issues with the new firmware?

I have a 6+ and 6. The 6 is working fine and properly. But the 6+ is having issues in connecting to my home wifi whereby it is always saying that "Incorrect password for network".

I have done hard reset on both my routers and my 6+. Not working at all. I have tried to get it connected to other wifi network(outside), it is no good.

Even if it does manage to connect to the wifi network but there's no internet access at all.

Any ideas guys?

I googled up and found some of the users are having the same kind of problem. Tweeted up Apple Support even they don't have a clue. All they asked of me is to send to the nearest service centre for hardware check.

Done all that. So, basically here are the steps I've done.

Solution 1.
1. Toggle WiFi ON/OFF.
2. Toggle Airplane mode.
3. Reset the phone.
4. Erase network settings.
5. Erase the content and all settings.
6. Reset my router to factory settings and re-configured.
7. Restore from backup (still ios9.3.1).

Solution 2.
1. Repeat steps 1 till 3 from Solution 1.
2. Erase the content and all settings.
3. Set up as new phone.
4. Reset my router to factory settings and re-configured.

Even after all these steps taken, the WiFi still failed. Sent it to Apple service centre and will take at least 14 working days for them to figure it out. Luckily, I took 2 years warranty. Who knows, I might get a new unit.