I'd like to share information with you. I flashed my DM7020HD and ve'got Err01 NO CA FOUND and hare is the solution:
1) connect dreambox DM7020HD service miniUSB into PC (likw win10 x64)
2) new device will be visible as dreambox dm7020hd but you need to install driver. I used:
https://drp.su/en/hwids/USB%5CVID_10...windows-10-x64 SiLabs-WinAll-USB_10.1.8.2466-drp.zip
3) started Univerzal DreamUP now with discovered COM port
4) turned off/on dreambox and DreamUP uploaded second-stage (web boot loader)
5) over LAN I was now able to fix my DM7020HD by uploading previous version of firmware