Soft-Bricked, can't get computer to detect device

So, i was trying to flash a stock ROM in Odin, and it failed, so now I'm soft-bricked. I was going to go ahead and retry but now I can't get Odin to detect my device. It's a Verizon S5, the G900v. I've installed drivers, uninstalled drivers, tried multiple cables and multiple computers and I get the same thing every time; "USB Device is unrecognized". I can only get it into download mode, but nothing will recognize it. Any help would be appreciated.

Soft-bricked D820n a51_ul after upgrading just firmware from OTA

Hello,
i have single sim d820 (europe)

Code:

---

***************************
Software status: Modified
A51_UL PVT SHIP S-ON
hboot-3.19.0.0000
radio-01.01.010_U10305041_08.01.50512
os-2.10.401.2
***************************

---

Before i messed it up it was unlocked and rooted and S-ON, then i wanted to install OTA and i flashed firmware.zip extracted from OTA zip file (bad idea). Now i'm unable to get my phone working...
What i can do:
-enter bootloader
-fastboot commands
-enter recovery

What I've tried and didn't work:
-flash stock recovery, lock, flash RUUk44.zip via fastboot (signature verify fail)
-flash stock recovery, lock, flash lollipop OTA (signature verify fail)
-flash TWRP, restore k44 backup (bootloop after reboot from recovery)

The question is, if I would somehow obtain firmware from k44 stock, is it possible to downgrade on S-ON using "fastboot flash zip" and then restore backup or flash RUU?
I cannot find magical RUU.exe for this model there are only zip files...
Guys maybe someone can dump kitkat firmware i would be grateful...
I appreciate any idea, please help me solve it :(

Advice on "unbricking" a soft-bricked stick

I've been scouring different forums for nearly a month now and can't find a solution that works for my situation. I resisted posting here, hoping to find the info on my own without any luck. I have a handful (6) of these generic MK809III Rockchip 3188 based sticks. All identical. I have no idea which Chinese manufacturer assembled them. Four of them work perfectly. Two of them have been corrupted by me. I inadvertently wiped out the build.prop files. The files are there, but they are empty. (I know this because the last one I botched, I could see the file in the open editor with no content, as a read-only. The moment I closed the screen... that was it.

Using the "hold the pin in hole, then power up, wait 5 or 10 seconds, then release the pin" method of recovery (sorry, I don't know the proper name) does boot it into recovery mode, but the screen shows this:
Failed to mount /mnt/external_sd (No such device)
Failed to mount /mnt/external_sd (No such device)
Failed to mount /mnt/external_sd (No such device)
one_data_if_exist->can't find databk partition
Formatting /data...
Formatting /cache...
Booting...
--- then, a stuck boot animation.

My problem, is that I cannot connect to these via USB to do anything to them. My system tools are:

Linux 14.04 LTS workstation
RK_Flashtool_1.7
Android Studio
Latest Android tools sdk
Other tools available to me: A Mac (running Yosemite OSx)

Notes:
- Adb drivers, I assume, are correct, because I can access the working stick computer via ADB
- The RKFlashtool will not recognize any of the corrupted units, or show that it is even connected
- Obviously, I cannot set the "Connect to PC" flag without the OS booted
- In a terminal window, adb does not show the usb device as being connected
- I do not have a back up for any of these. I tried, but both Clockwork and TWRP would not recognize the unit to permit a backup. The unit is recognized as: "get_dongle_3188".

I really need some advice. I must be overlooking something, I admit to be very new to Android. I wish it were possible to backup one of the working units, and install it on the corrupt units. But no backup app was installed in the boot loader of the corrupted (that I'm aware of).

Thanks for your time!

soft-bricked galaxy s5 g900f

My s5 g900f recently started having this weird battery issue where the battery would go from 100% - 0 in under an hour, But before I got to replace the battery I jus woke up one morning n the phone was off, tried putting it on after recharging but all it did was continuously show the Samsung logo and reboot. Got a new battery but no change, plus I only seem to have access to download mode.

Phone softbricked while rooting, can only access download mode

...and now I have no idea what to do.

Windows 10 doesn't like the phone (as in "unknown usb device error 43"), I have no idea what firmware to flash or what tool to use.

Model is D855

I appreciate any help

Galaxy s3 Nand write fail, softbricked. Can't get normal methods to fix it.

Hello! I have been rooting and flashing roms for a while now, and after sticking with a cm mod for a while i decided it was time for a change. I foolishly didn't back anything up and just flashed a rom to check it out. I have a Galaxy s3 19300 unlocked version (i have it on a plan for cricketwireless). I cannot get odin to work for me to flash a new custom rom, a stock rom, or even begin trying to flash. Odin either gives me the nanad write error or the program stops responding. I have samsung drivers installed and really need some help. I'd appreciate any help on getting me one step closer to a working phone. Thanks!