Is my Smart Soundbar 900 bricked?

I bought a certified refurbished Smart Soundbar 900 in December. It has mostly worked, but I've had a few glitches, which seems to be common. Yesterday I tried forcing an update by holding down the "music" button. It downloaded an update, but it got stuck installing it (with the left-to-right pattern on the led bar.) It's been stuck since then.

The soundbar does nothing but perpetually show the left-to-right pulsing LED. It does not respond to the remote in any visible way. It has never been connected to wifi, and it does not broadcast a wifi setup SSID. It does seem to successfully connect to ethernet, but only for about a minute at a time. After that it drops off for about thirty seconds, then it reconnects and repeats the cycle.

I've already gone through troubleshooting with Bose, and they've offered to replace it with a Smart Ultra Soundbar. I'd prefer to keep the Soundbar 900 if possible, partly because it supports Google Assistant, but mostly because I don't want to deal with shipping it back to Bose.

I have tried:

• power cycling

• replacing the ethernet cable

• putting it into recovery mode (the LED flashes green for ten seconds, but then it goes back to updating forever)

• factory reset from the remote (no response at all)

• updating the firmware via IP (I can connect and begin the upload, but it gets interrupted when the soundbar drops off the network again)

• updating the firmware via USB (no response when I try to use the remote to put it into service mode)

Is there anything else I can try?