[Fire HD 8 and HD 10 Android Development] DJames1:
Ok, I'm trying this on my new Fire HD 8 tablet, and it wasn't a great start, but I think we got there...

Following the instructions, I skipped connecting to a network and went straight to the home screen and then Setup, I enabled Developer Mode and USB debugging on the tablet, plugged into the USB port on my Win7 computer, it says "Installing driver...", and then says it couldn't find a driver. ** mistake here?

I installed the Fire Device ADB Drivers.exe from the first post of this thread, and that appeared to work.

When I ran the Toolbox, it reported that there was no driver installed, and asked if I wanted to install it. I said yes, and it gave a bunch of "Directory not found" error messages. Then said it couldn't find a Fire device and couldn't proceed. I uninstalled Toolbox, and tried again. The ADB driver says it's already installed. The device just gives me a negative beep when I plug it in, and for the Fire USB device that appears in Device Manager it says "The drivers for this device are not installed. (Code 28), There is no driver selected for the device information set or element. To find a driver for this device, click Update Driver.", and the Update online option says it can't find any driver for this device. If I re-install Toolbox and try to run it again, I now get an Avira anti-virus security alert for "HEUR/APC (Cloud)" for the file Notifications\SetConsole.exe, which is blocked. I read the note about batbox.exe being a false positive, but this seems to be a different file. Has the component that triggers the virus indication has moved?

So trying to guess what went wrong here, I noticed that after I returned to the Win7 computer, removed all the ADB and Toolkit stuff, turned off USB debugging mode, and connected the tablet for file transfer, it did connect correctly. I wonder if I got the order wrong above (where I marked), and turned on USB debugging mode BEFORE installing the regular driver. With the tablet in USB debugging mode it connects just fine to Win10 and installs the required driver, but apparently not with Win7.

Tried again on my Win10 laptop, following the same process as with Win7. This time I got a positive-sounding ding when I plugged in the tablet, and it shows a driver installed and working (USB debugging mode was still On). That sounds better than the Win7 machine. But when I try to install the Fire Device USB driver I get the error "Writing to ... adb_usb.ini file - Failed to write file" (running the installer in Admin mode from an Admin account, so there shouldn't be any directory protection issue). So I just tried it again, and this time the Fire Device USB driver installation successfully wrote to the file, although there was no difference in procedure.

I installed and ran the Toolbox (with anti-virus disabled). It got to the point where it's waiting to see a tablet plugged in, but it didn't see the tablet already plugged in with USB debugging enabled. Unplugged the tablet and replugged - nothing. Removed and re-installed the Toolkit. Rebooted, tried again - nothing. The Toolbox flashes some additional messages in its window way too fast to see (like 1/10 of a second) in between prompting for the tablet to be plugged in, impossible to read. I finally managed to freeze the screen long enough to read, and the 0.1 second flash messages said that ADB wasn't authorized, which reminded me that I had to authorize the USB debugging connection on the tablet end. No idea why nothing appeared on the tablet earlier, but it did when I unplugged and re-plugged once again, so good to go.

Ok, now I see the Toolbox interface on my Win10 laptop... and the first few operations seem to be going smoothly: block OTA updates, reboot, sign in to WiFi for the first time, install Google Services...

But one more hitch: after the initial setup, I checked to see if Echo Show services were available, and they weren't. It turns out that an update from Fire OS 6.3.0.0 (pre-installed) to 6.3.0.1 is required to enable Echo Show mode. So I had to perform an OS update, and then re-apply the OTA blocking. Fortunately the OS update did not remove Google Services or Google Play.