I've tried several times to update to 5.4.1[7], but keep getting the following messages (see attachment). Any ideas? (Did search here but didn't find an answer.)

Are you connecting to the H9 from an iOS device via Bluetooth?  We've seen these errors come up sometimes when other users tried to update that way.  If so, if you connect your H9 to a desktop computer using Bluetooth instead, you should be able to update that way.