Acer DA241HL - system reset from bootloader
Summing up from the comments:


No "reset" will ever roll back any system updates applied. For that, you would have to re-flash the original ROM.
For the device to show up with adb devices or fastboot devices, you must have your computer configured accordingly. If your computer runs Windows, you will need a special driver (Koush's Universal ADB driver might help you out here, in case you cannot find a specific driver for your devices). If it's Linux, you might wish to consult my answer here, for a Mac it might be similar. Further helpful hints can be found via our adb tag-wiki.
As you have multiple identic devices, some updated and some not, you should be able to utilize dd (see also this wikipedia article for a starter) to clone all partitions of one device and apply that to others. As partition structures are quite device specific, I cannot give you accurate details here; a little research might be helpful especially on sites like XDA Developers. A custom recovery can be used for this as well: check out our nandroid tag and its tag-wiki for details on that.