Adding to Hwops queue.  Please take a look at build16-b1 and bring all the devices back online.  Thanks

All devices that are connected are on, responsive to touch, and responding to ADB. Let me know what else I should try.

chrome-bot@build16-b1:~$ /b/build_internal/scripts/slave/android/adb devices
List of devices attached 
ZX1G22KG9L	device
ZX1G22K86J	device
ZX1G22KB72	device
ZX1G22KFD7	device
ZX1G22K6GS	device
ZX1G22KBZ8	device
ZX1G22KB64	device

+pschmidt as he's dealt with failing bots a lot and has a near magical ability to fix them

Peter, any advice on what to try?

ZX1G22KBZ8 is still blacklisted and the other device is still listed as (error)

Just did the following to clean up the device state confusion.  It should be cleared up starting with https://build.chromium.org/p/chromium.perf/builders/Android%20Nexus6%20Perf%20%282%29/builds/2142

rm /b/build/site_config/.known_devices
rm /b/build/slave/Android_Nexus6_Perf__2_/build/src/out/.last_devices
rm /b/build/slave/Android_Nexus6_Perf__2_/build/src/out/bad_devices.json

Ok all the devices are listed now, but unfortunately ZX1G22KBZ8 is still blacklisted.

I never double checked the state of the devices yesterday.  Anyway ZX1G22KBZ8 was being shown offline.   adb showed it as being offline, but the device showed that usb debugging was enabled.  I power cycled the device.   Let's leave the ticket open for now.

Bot is green! Thanks all!