Android-tools does not find device

[Paul Smith]

Dear All,

My Android tablet is stuck on

Fastboot mode.

I have tried to reboot it by pressing POWER and VOLUME UP keys held
simultaneously, but with no success. Consequently, now I am trying to
use

android-tools.

However, when I run the following command, no device is found, in
spite of the fact that the table is connected to my computer running
Fedora by a USB cable:

# adb devices
List of devices attached

#

Any ideas?

Thanks in advance,

Paul