MY SE wont wake up

It's still working, the phone rings, the alarm goes off but none of the buttons wake it up - I have to take the battery out and it's fine again until it goes to sleep

I know the hardware is fine - the problem is the software has become corrupt somehow

I have replaced the battery, master reset, upgraded latest software - nothing works

I dont know anything about SE phones and i'm struggling to know what other software is left to be corrupt

Only thing that's left is de-branding area of memory - albeit my phone isn't branded

How would i de-brand my 6 month old W890i or any other soft/firmware ideas??

Deliberately left the model to the end because i'm open to all suggestions before i throw it

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