Backup Data from Malfunctioning(Soft-Bricked?) not-Rooted Locked M7

Hi,
My One M7 started malfunctioning all of the sudden and now cannot boot android and stuck at HTC splash screen.

I would like to recover contacts and data(pdfs, images) from the phone.

The device is not-rooted, locked(as it seems in bootloader) and stock rom is installed.
On my PC drivers are installed(ADB mode) and ADB, FastBoot up-to-date.

When I'm in HBOOT 1.61 I choose fastboot mode and I plug the phone via USB2 to the Win10 machine.
I can see fastboot USB in red and send the command

Code:

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fastboot devices

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it returns the serial of my device.

But when i try

Code:

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adb devices

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command i get empty list.
So i cannot backup.

I also tried to
unplug USB and plug it back in

Code:

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adb kill-server

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Code:

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adb start-server

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Code:

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adb devices

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But still get empty list of devices.

Also tried the recovery option in bootloader but I get empty list of devices for both

Code:

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fastboot devices

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Code:

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adb devices

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How can I backup my data?
Is it possible to unlock the device from bootloader install custom recovery(with backup features) without losing data?


Any help is much appreciated!