z5c Back Button, Home Button not responsive

[zero_vertical]

Suddenly today, all my lower screen buttons (back, home, drawer) are completely unresponsive.   Multiple restarts.

sD card was getting full, so cleared a bunch out.

Battery was at 60% or so.

Installed a new app this morning (voice recorder), but cleared cache and deleted it.   

Would hate to factory reset this thing.   Not even sure how to do it.   What are my options?

[Phy]

Repair the phone with Sony PC Companion.
http://support.sonymobile.com/gb/tools/pc-companion/

[Phy]

Before you repair the phone, you could test the touchscreen.

1. Settings
2. About phone
3. Test
4. Test the touchscreen

[Phy]

You can also test if you encounter the same problems while on safe mode.

How to boot on safe mode
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

How to boot on safe mode on Lolipop
1. press and hold the power key
2. once you get the pop up menu 
3. press and hold "power off" 
4. Boot on safe mode should become available

[zero_vertical]

Booted into safe mode (holding "-" volume key until I got to home screen.   safe mode tag is visible in lower left.

Back, Home and Drawer buttons still not working. 

Tried clearing cache on xperia home app, but "clear cache" buttton didn't appear to do anything.   

[zero_vertical]

Tested touchscreen.  All of it worked but the bottonm strip where the button are.   It failed by timing out (because I couldn't press no!)

[Phy]

Contact your local Sony Xperia support it seems to be a hardware issue.
http://support.sonymobile.com/global-en/contactUs/

[zero_vertical]

I bought a non-US release months ago, because I wasn't sure it was going to make it stateside.

I don't think I'm going to be welcomed by anyone for a service issue.

Love this phone.   What happened this afternoon!!?

[Uliwooly]

@zero_vertical

Have you repaired the phone with PCC as suggested above?

[zero_vertical]

So I was on the way into work yesterday, planning to factory reset the phone, when the sun caught the lower corner of the phone and a hairline crack gleamed at me.

Turns out, there is an almost invisible crack in the lower corner from the bottom terminating at the side, exactly at the top of the black navigation bar.

New screen is $200, but parts are 3-4 weeks out.  I can't wait that long, so I bought a new one.  I'll just repair this one and keep it as a backup.   In the meantime, the app "back button" has kept hte phone pretty functional.  It's just a customizable widget that floats on top of whatever you're working on, and has a home, back and recent (drawer) button.   

Thanks to all for your help!  

zero