Soft rebooted it to get it to become adb aware.

List of devices attached
07a1ae29	device
0585c0cd	device
06d8a77c	device
07a04273	device
0585ea58	device
07086a3b	device
059959cd	device

Re-opening; still offline as of the latest build: https://build.chromium.org/p/chromium.perf/builders/Android%20Nexus7v2%20Perf%20%282%29/builds/2366

Hard reset + a new cable for 059959cd	device

I noticed that 059959cd dropped offline again.  I just re-flashed it.  Effective starting with https://build.chromium.org/p/chromium.perf/builders/Android%20Nexus7v2%20Perf%20%282%29/builds/2382

If it still behaves badly I'll swap it out.

Following on from #4, this is still red and purple. Looks like it needs swapping out.

I need to find a spare.  In the meantime I went ahead and re-flashed it.  That will be effective starting with https://uberchromegw.corp.google.com/i/chromium.perf/builders/Android%20Nexus7v2%20Perf%20%282%29/builds/2391

I have a replacement N7 flashed to KOT49H ready if needed.

Flashing that one did the trick.  It's been solid.