After trying to get my bkool pro smart trainer to update to the most recent version for almost two weeks, I finally solved the issue tonight. The official FAQ just states that you should stop anything related to bluetooth and that the ANT+ dongle should be right at the base of the trainer. I had done both things – even stopping any Garmin related products installed, but nothing helped. The firmware update would start, but after a couple of minutes (or a many as ten), bkool indoor would error out.
The solution: A new USB controller card. Apparently the USB ports on the motherboard introduced too much noise on the connection, and since ANT+ (or bkool, not sure) doesn’t have any proper error correction to detect errors on a smaller level and resend USB packages, it seems there was an error introduced somewhere in the firmware update, and the end checksum failed.
A new VIA-based USB PCI-card from Ebay solved the issue, and now my firmware is upgraded! Yay! (the trainer worked just fine except for that, so it was still usable – but I had a bug appear that the firmware should fix (or maybe that was caused by noise on the USB bus as well? We’ll see. Zwifting away in a couple of days)!