Hi,
Have you had a look at the Frequently Asked Questions (FAQ)? for the "Hard drives" section?
https://www.intenso.de/en/support/faq
From the above link:
Why does the hard drive not show a function, resp. the LED does not light?
Connect, if available, both connections of the supplied Y-USB cable, to ensure adequate power supply. With external 3.5” hard drives please check whether the supplied power pack is properly connected to the socket and hard drive and whether you have pressed the On/Off key of the hard drive.
To exclude a defective USB slot as error source, plug the external hard drive into a different USB port. If this procedure does not lead to success, please check the functionality of the external hard drive on another PC. If the external hard drive works on this other PC, there is a configuration or hardware problem on the first PC. In this case please download all updates for your operating system and check whether a firmware update is available for your mainboard.
If the external hard drive does not function on the second computer either, there is most likely a defect on the external hard drive. In this case please contact your dealer and carry out a complaint.
If you have connected the hard drive via a USB hub, please check in any case whether the USB hub is correctly connected to the power pack to guarantee a proper power supply.
Best regards,
Leon