I know the SBBs from Home Depot have historically had some challenges updating FW.
I did have an initial struggle getting the Beta 3.5-beta update applied.
After a hang at 89%, and a failed Cancel Update button tap in app (SBB device fell offline and not able to get out of Syncing… loop), a hard power cycle enabled me to re-initiate the FW update and this time it completed.
Just an encouragement to any forum users that have that HD 4 spd universal Smart By Bond receiver that a reboot and quick initiation of FW update was successful.
Indeed this has been a problem on all Smart by Bond and even some Bridges.
We’ve fixed the problem in v3.5+ firmware, so once you’re upgraded you will be in good shape.
Two workarounds: (1) power cycle (or PUT sys/reboot) and then immediately attempt the update as you did @residualimages [this works about 50% of the time, so you can retry at most 3-4 times and it will finally work], or the more reliable (2) hold down the Power button on the remote, reconnect to the Bond Config AP which appears, and then hit + in the app to setup again on Wi-Fi. The app should propose the v3.5 update which is then loaded from the phone over the Config network. This seems to be far more reliable.