T470s stuck at BIOS without docking station

My T470s does not start (after shutdown) and get stuck at Lenovo BIOS screen indefinitely. However, it starts perfectly well when the docking station (Lenovo ThinkPad dock) is attached. I have tried updating the BIOS to version 1.30 (latest), but still the problem remains.

I have a dual boot (Windows 10 + Ubuntu 17.10). The problem started after suddenly one day on startup the laptop displayed a simple message saying that the laptop is updating (probably BIOS) and I shouldn't power it off. After a while it started normally, but then didn't start after shutdown.

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