07-15-2019 05:50 AM
Try toggling the Thunderbolt BIOS Assist Mode in BIOS Setup -> Config -> Thunderbolt.
1. set it to "Enabled", then press F10 to save/exit. At the red "Lenovo" screen, you should see something like "configuring Thunderbolt..."
2. set it to "Disabled", then press F10 to save/exit. You should see the "configuring Thunderbolt..." message again
Just make sure the setting is "Disabled" in the end, and then try your tests again. If you end up getting "0x20B SDK_NO_CONTROLLERS" from the flash tool no matter what you do, I'm afraid that's a hardware problem and will need warranty service.