Do not turn off the power until the progress bar reaches 100% and the device reboots. Common Issues Fixed by Firmware
: Fixing stretched or squashed images on modern TVs.
: Updates often improve compatibility with local signal frequencies.
: Check the D-Color official website first. They occasionally keep a repository of software updates for their receivers.
Since official manufacturer support for older DVB-T2 boxes can be spotty, your best bet is to look at dedicated electronics repair and community forums.
and go to Menu > System > Software Update > USB Upgrade .