How can I recover my phone from "No command" bootloop after failed upgraded process

[AC Question]

Hi, I have a Oukitel U7 Plus and I'm stick in a "No Command" bootloop.
youtube v=0kjIBdPUkAs
Trying Vol Up + Power doesn't bring me in the Recovery mode.
What are my alternatives to reflash the system?

- Boot from SD-Card?
- ADB?

Best regards
Thomas