Yes, I know how crazy it is that you have to find an old Windows machine to update a brand new KL25Z. Unfortunately, the factory firmware installed on new KL25Z boards was written when Windows 7 was current, and Microsoft made changes in Windows 8 that are incompatible with that old firmware.
The easiest way to deal with this is to find an old machine running Windows 7 or XP. But if that's out of the question for you, there are two alternatives. Both require some extra work, but they'll let you do the upgrade with your existing machine.
The firmware incompatibility in Windows 8+ apparently is due to disk search features that Microsoft added in Windows 8. When you plug in a USB disk, Windows automatically writes to the disk to create a hidden search index file. The older KL25Z boot loader mistakes the hidden file for an attempt to download new firmware onto the device; but since it's not a valid firmware download, the boot loader goes into an error mode and refuses to listen to any more requests. This blocks any subsequent attempts to download legitimate firmware files.
One way to solve this is to change your Windows system settings to disable the new indexing service that causes all the trouble. This requires messing around in the bowels of Windows, so if RegEdit makes you queasy, you might want to skip this approach and try a different option.
This method was first described (as far as I know) by Erich Styger on his MCU on Eclipse blog. Please see that article for a more thorough explanation.
Here are the steps:
Now you're ready to attempt the firmware upgrade on the KL25Z. Be warned, though: you have to do the file copy as quickly as possible after plugging in the KL25Z. Apparently, the steps above prevent Windows from writing the drive right after you plug it in, but Windows might still try to do a write if you leave the drive plugged in long enough. So you should try to move quickly.
Other than this race against time, the upgrade itself works just like in the main instructions.
You can now verify the upgrade. Plug the programming port back in (without pressing the Reset button). The KL25Z thumb drive should appear. Open the file SDA_INFO.HTM. Check that the reported firmware version matches what you just downloaded.
If you don't want to make the changes to your system settings described above, or you can't get that approach to work, you can solve the upgrade problem by running a virtual copy of XP or Windows 7 on your existing operating system. This approach is fairly complicated, but it doesn't require any changes to your system settings and doesn't require any special timing.
The first thing you should do is print out the instructions that the Pinscape config tool displays for doing the firmware update. The config tool won't run on XP. That's okay, because the config tool doesn't really do anything during the update process anyway except display the instructions. But you can't run it to view the instructions in XP, so you'll want to have a copy handy before you start. To do this, go to the "Set up a new KL25Z" page, click past the warning about Windows versions, then click "Show All". You can now print the page (there's a button at the bottom to do this). If you have a two-monitor setup, no need to print; just leave the instructions on one screen while you run the XP VM on the other screen.
The next step is to download and install VirtualBox, which is a free Virtual Machine manager. Start here: virtualbox.org. Download the latest version and go through the setup procedure to install the product on your computer.
Now we get to the really time-consuming and difficult part. You need to create an XP or Win 7 VM for VirtualBox. There are basically two options for doing this:
Once you have your XP/7 virtual machine running, shut it down by going to the Start menu within the virtual OS window and clicking Turn Off Computer. Wait for the VM to shut down. The VM window will close when it's done.
Now go back to the VirtualBox VM manager window. Right-click the VM in the list and select Settings. In the Settings window, select the USB page. There should be a checkbox at the top labeled "Enable USB Controller". Make sure it's checked.
Plug in the KL25Z via the programming port. Click the "+" button next to the "USB Device Filters" list. You should see an entry in the pop-up list starting with "PE Microcomputer Systems Inc". That's the KL25Z programming port. Click it to add it to the list. Click OK.
Unplug the KL25Z.
Launch the VM by double-clicking it. Wait for it to finish booting. The XP/Win 7 desktop window should be showing and the disk should be done grinding away at startup tasks. Now plug in the KL25Z. If all went well, it should appear on the XP/7 desktop and not on your real Windows desktop.
Now get out that printout we made back at the beginning of this whole mess! Follow the instructions to download and install the first .SDA file within the XP/7 box.
At this point in the printed instructions, you'll be asked to unplug and re-plug the KL25Z. Things get a little hazy here. You might need to add a new VirtualBox USB filter. Try re-plugging the KL25Z and see which desktop it connects to. If it connects to the XP/7 desktop, all is good. If it connects to your regular Windows desktop, go to the USB device menu in the VirtualBox controls, find the un-checked "PE Microcomputer Systems" item, and check it. After you check it, unplug the KL25Z and plug it back in. This time it will hopefully connect to the XP/7 desktop rather than your ordinary desktop. If not, you might have to shut down the VM and repeat the USB Filter process we did earlier from the VirtualBox Settings dialog.
Once you get through the whole procedure within the XP/7 VM, disconnect the KL25Z and shut down the VM (Use "Turn off computer" from the Start menu within the VM window, and wait for the VM window to close). Now plug the KL25Z back in, via the programming port.
If all went well, you should have a drive on your Windows desktop labeled FRDM-KL25Z. The drive label is very important. If it's FRDM-KL25Z, everything worked and the device should be ready to use in your modern Windows version! If the label isn't FRDM-KL25Z, something must have gone wrong somewhere along the way. Try going back through the process above again. If you can't get it to work after carefully repeating all the steps, post on vpforums.org and hopefully I or someone else will be able to help you troubleshoot.