Well, you’re not alone. I had a similar mishap recently when I upgraded with a version of Wildcat for 2.81.
I had the marco-sinnati firmware. Sys and App. Loaded that and all was well.
The new 2.81 firmware might be overwriting the sys in some part. I recovered the working of my DSO but the SEEED logo has gone with some pixel dust in place of that. At least that is better than losing the DSO altogether.
This page has nearly all you would need.
seeedstudio.com/wiki/DSO_Quad