Hello, my Motorola Razr I xt890 was completely stock, bought simfree. No rooting or unlocking, no modifications, nothing.
When I attach a USB cable the green light turns on. Nothing appears on the screen. If I hold down the volume buttons and the power button, the green light eventually turns off, but nothing appears on screen.
When the phone is attached to my PC via USB, Windows makes the "USB connected" and "USB disconnected" sounds, but nothing appears on My Computer.
You won't believe it, but the same exact thing happened to me last night!
My BL is also still locked, running JB, but I used twerkmymoto to get root and didn't do any modifications lately, meaning nothing could have triggered the brick.
So this is what happened to me:
I used my phone, got the 10% low battery warning but was too lazy to recharge it.
Checked my phone several hours later, saw the led flashing in white, meaning I got a new notification (Whatsapp, FB,...) so I tried to turn it on, but nothing helped. Not pressing the power button long, short,...
I thought my phone is just completely out of battery and will work again once I charge it.
So I connected it to my PC, tried adb reboot, didn't work, checked adb devices and it listed me my device but with the status "offline". I thought, maybe thats because I have a lock screen security pattern activated.
Since we can't unplug the battery, I hit all 3 buttons then (power, vol+,vol-), and it "restarted", meaning its in the same stage ever since.
I also turned my phone "on", meaning that the green led is on and let it on until it didn't do anything anymore, meaning the battery completely dried out.
Then I hooked it up to a charger overnight for the full time with no interruption, but it still didn't charge.
Now here is what I tried since then:
power, vol+,vol-
power, vol+
power, vol-
power, vol+,vol-,camera button
Charging via outlet charger
-->green led turns on, nothing else, no display, no vibrate, no M logo
Charging via external battery
-->green led turns on, nothing else, no display, no vibrate, no M logo; charger doesn't get warm, meaning the phone battery doesn't get charged
Connecting via USB
-->green led turns on, nothing else, no display, no vibrate, no M logo, Windows makes the "USB connected" and "USB disconnected" sound, phone is connected for around 2min30seconds, is disconnected for 30sec and reconnects then
When the phone is conected via USB, in the device manager I see a device called Medfield but the system can't find any drivers, (I have RSD 6.1.6, the Motorola Device Manager and this:
https://software.intel.com/en-us/android/articles/intel-usb-driver-for-android-devices installed)
RSD of course didn't find any device yet, since no driver was installed yet.
So I manually selected a driver for the medfield device, here is a list of possible devices I can chose from:

I don't know whether I have those driver because of adb minimalist, the Motorola Device Manager or cause I use the Nexus Root Toolkit for my Nexus
I tried the ADB Interface v10 driver (since its the newest) and the Composite ADB Interface v10 and both work, meaning the device manager doesn't show me any errors.
RSD then shows the device.
fastboot doesn't find the phone, but RSD finds it but can't flash anything since it can't start the phone in fastboot mode
Now what is there that we can do to get it fixed? I have very important data on my phone that I'd hate to lose, so if somehow its possible to get it to a point where I can adb pull all my data, that would be awesome!
Again, I didn't play around with any system files, its still a locked BL, no custom rom and my phone only ran out of battery and doesn't boot up anymore.
Thanks a lot in advance!
EDIT:
I read a bit more here:
xsftk to flash dnx and ifwi:
http://forum.xda-developers.com/showthread.php?t=2184877
http://forum.xda-developers.com/droid-razr-m/help/droid-razr-m-hardbrick-fix-t2934432
http://forum.xda-developers.com/showthread.php?t=2533049
really good one:
http://forum.xda-developers.com/moto-x/general/how-to-resurrecting-bricked-moto-x-t2629057
http://forum.xda-developers.com/droid-ultra/general/droid-ultra-maxx-brick-recovery-t2830806
http://forum.xda-developers.com/showthread.php?t=2149889
Now from what I understand, the bootloader got screwed up (don't ask me how this is even possible with a locked BL)
I still wonder, whether it really is a BL / kernel / recovery error or my battery just fried. Any thoughts on how I can find out whether its the OS or the battery?
Looks like my next step is to get a factory cable but I don't think this will help cause if fastboot can't find the phone then there is nothing to flash.