T8sg No splash screen or USB

Friend gave me a non working T8sg. The splash screen doesn't show when turned on (blank screen, but on). Turned it on in USB mode and there is no USB symbol. It does show as D: drive when connected to computer and all the files are there. I copied the files and went through DFU update and latest nightly build 5.0.0. Still no splash screen or USB symbol. When I put it in USB I can see the new files that I loaded. Could it be a solder connection? Thought I would ask questions before it becomes a donor for parts.
Anyone have an idea?
Thanks

Thanks Vlad. Took the back off and looked around and found the ribbon cable tucked underneath where it should have been, it looked like it was in place but it wasn't making the connection. It's now working like it should.
So thanks again!