Flashing screen

[sy8s]

Earlier this week my Xperia M5 developed a fault where it gives a "System UI has stopped" message and it then starts flashing the background image. Only thing I can do is restart it or turn it off. Have tried using the reset button under the SD/SIM cover but problem comes back.  

Have seen a suggestion to start it in Safe Mode by using the Power button but that option is not offered.  Problem starts 2/3 minutes after I turn the phone on.

Even if I can't get the phone to work again, I would like to recover the contacts. 

[Uliwooly]

@sy8s

what if you repair the phone with XC?

[wty]

Has anyone resolved this my phone started last night with the flashing screen tryed to get into the settings but cant 

[sy8s]

Update

Despite the flashing screen, I managed to backup my contacts to a PC using Xperia Companion.. The backup took  the best part of an hour by the way.   Elsewhere I found a way of extracting the details from the backup file to a .vcf file.

I then used Xperia Companion to reset the software, again this was very slow.  Once this had finished, I booted the phone and started setting it up. 15/20 mins later, the screen started flashing again!

[Wanessagsoares]

My M5 recently had a problem on the screen (bottom), a bar of 2 centimeters resembling a bar code. Here in Brasilia does not have authorized of Sony, what to do in that case? This defect is especially annoying when it comes to taking pictures ... I'm waiting.

GT