Constantly vibrating wont turn on and flashlight is on

[Zazu272]

Hi my misses phone is a z3 5.5 good phone till I found it black with the flashlight on then it began to vibrate constantly iv tried reseting it with the power and vol up buttons and the little yellow one inside I'm completely baffled by this we bought this phone second hand in perfect condition not been in water or anything it's acted up by going black before which I sorted but this is just buzzare really hope someone can help us as iv not got warranty or contract to fix this iv left the phone to do it's thing till it dies and then I'm gonna charge it and see what happens please sony help 

[Qatrium]

@Zazu272

Did you press the yellow button beneath your SIM tray flap long enough? You need a few seconds before releasing it.

[Zazu272]

Yeah I held it for quite a while too done both methods a few times over just went to the phone this morning and it's still doong the same thing after all night I was hoping it would of died it's just red raw now still vibrating away 

[Qatrium]

@Zazu272

I'm suspecting a hardware issue here, and even the software workaround ( software repair using Xperia Companion ) will be tricky to be performed in your current device state.

I think you should contact your Local support and get your phone inspected by a professional.

[Zazu272]

I can't just go to a sony centre as the're isn't one near me and I'm hoping there's another way to fix this nothing happened to the phone just randomly started doing it not like I dropped it or anything