Sony Xperia L4 keeps rebooting and won't turn on

[Beldon]

I have a Sony Xperia L4 - it keeps rebooting and won't turn on long enough for me to do a factory reset. I downloaded the Companion App and again, it can't detect the phone because it's not on long enough. 
My data is backedup. 
I just don't know how to make it stop - likely it's an App causing it. But I cannot get to the route of the issue without the phone being fully on. It was 83% charged last time it was on. 
I also need to try and get the data on (as it's turned off) in order to get the Companion App to be able to connect with it, but again - it won't stay on for long enough. 
HELP!?

[Chris_B]

@Beldon have a read of THIS it should help you. 

[EssexBoyEE]

If you've got issues with the Phone your better off using the USB Data Lead with the Sony Software.

But try this first, Hold down the Power and Vol Down buttons together maybe for a long time, a few mins, untill the Phone Vibrats or Powers on

[Beldon]

Thank you - I've tried that multiple times and it doesn't work.

[mikeliuk]

Hi @Beldon ,

Can you get the device into Safe Mode following online instructions?

The procedure seems to be a variant of the above where a button is held longer than described above.

[EssexBoyEE]

Also try Vol Up and Power and or both Vol Up and Down together and Power Button.