The Slate 21 device is quite good, although it's really low on specs. Only 1GB of RAM and only 8GB Space inside (although you can stick a full size SD card inside).
You can read some reviews about the device here, here and few people wrote about it on Amazon and you can read their reviews here.
Technically, this machines IMHO begs to be modified. You don't have the issues of tablet heat, so you might want to overclock it, and maybe do some other software modifications..
In order to modify anything on it (that means: changing firmware, recovery, boot loader etc) you'll need to unlock it first, and here are the instructions how to unlock it. After unlocking it you'll need to root the Slate, and so far I failed to find a way to root it (I tried several methods, including the nVidia Shield way and the TN7 way - it doesn't work), but if you want to try it, go ahead and if you manage to root it, I'll be happy to hear about it and publish it here (with credits to you).
So without further ado, lets get started.
Warning: The following steps WILL VOID YOUR WARRANTY! I'm not taking responsibility if your device will brick, explode or anything else, you've been warned!
- In order to actually get access to the machine, you'll need a Male to Male USB Cable, like this one, which you can order from that page or simply buy from your local tech store such a cable. Connect it from the Slate's side USB port to your PC. Your Windows (or Mac or Linux) will recognize the device as MTP.
- Make sure you have the latest updates for your Slate. Unlocking the device will not let you receive automatic updates, so click on the Settings, scroll to the bottom, click on the "About tablet" and then click on System updates, and then click on the "Check Now". If your device has updates, you'll see it there.
- Now we'll un-hide the Developer options. Click on the "About tablet", and then click 7 times on the "Build Number", and after clicking 7 times, you'll see on the left side "Developer options" - click on it, and click on the "USB Debugging". In my Slate, the device rebooting after clicking on it, so if it's rebooting on your slate, let it reboot.
- Install ADB and fastboot On your Windows machine (instructions are here) and after installing ADB and fastboot, connect your Slate to your Windows/Mac/Linux. In Windows, you'll see a new device, and ADB device. If you get an "unknown device", or don't get anything, then follow the instructions here.
- Open a command line prompt and run the adb devices command. It should show you your slate as a number with the word "device". If not, check the instructions on the link above and make sure you don't have "unknown device" - or else ADB won't know how to talk to your device.
- The next part is critical if you have any data that is important to you, make a full backup before going any further! unlocking your slate will erase everything you installed or uploaded to your slate. I recommend using the Holo backup app if you're a Windows or Linux user. Later you can restore all your apps and content with a single click :)
- Run the command: adb reboot bootloader
This will reboot your slate and will give you a simple menu. don't select anything.
- Run the command: fastboot oem unlock
This will show you a simple menu to select if you want to keep it locked or unlock the device. Use the Volume buttons to choose your option (select: unlock) and then press brightness up key (the button below the volume keys).
Here comes the "scary" part - you won't see anything on the screen after selecting to unlock. Thats OK. Wait for a minute or two (patience, friend) and if your slate still doesn't show anything, then press the power button for 10 seconds (don't let go), and if you still don't see anything, press it again for 10 seconds, your slate will reboot and you'll have to setup everything from scratch (entering your gmail user, pass etc...)
- Congratulations, your device is unlocked. If you want to re-lock it (and again, this will erase everything on your device!), follow the steps above and select "lock". I don't know if the slate "phones home" to report if it's locked or not, so I don't know if you warranty will be restored (probably not).
The next steps which are still unknown are rooting the slate, and installing a new recovery. While finding a way to permanently root the slate will be a matter of short time, recovery is another thing and requires to create a new image with modifications for the slate.
I'll keep you posted for any progress that I'll make, so subscribe to this post :)