Is the Raspberry Pi booting at all? On my Pi 3, the red led is coming on, and the green led is flashing from time to time.
Have you put the SD card in the slot on the Raspberry Pi?
I just upgraded Kermit to RPi3 from RPi2. Initially the internal WiFi was iffy, the battery status didn't work and the Pi-Top specific function keys didn't work. I placed a ticket and Tech Support advised me to install pi-topOS Jessie for RPi3. That has worked a treat and now everything is great.
For Alex, I'd suggest reviewing the installation. Check the GPIO connector and the other end on the pi-to Hub. I understand its easy for the Hub end to be connected backwards. If that happens then you get a lot of weird errors. Recheck the seating of all other connectors as well.
The microSD card slot is no longer spring loaded on the RPi3 and the card goes in with the edge connectors upwards. Make sure its inserted fully.
The screen you're getting shows that video is working. If your SD card is operating correctly you should get a text boot sequence. I don't understand most of it, but it shows activity and helps when you see a lot of OKs.
Have you installed pi-topOS successfully on your SD card? You may have a corrupted OS. Mine did the same before I re-installed pi-topOS.