Beaglebone Black health-check job is failing at restart

Issue Background

Health Check is getting about 1/2 way done, then fails when trying to restart the BBB.

Issue description

Partial logfile:

onnect-device Connecting to device using 'telnet 10.0.0.50'
connect-device duration: 0.00
start: 2.5 uboot-retry (max 120s)
start: 2.5.1 reboot-device (max 120s)
start: 2.5.1.1 soft-reboot (max 120s)
reboot
reboot
reboot -n
reboot -n
reboot -n -f
reboot -n -f
soft-reboot: Wait for prompt The system is going down for reboot NOW. 120 seconds
Trying 10.0.0.50...
reboot
reboot -n
reboot -n -f
telnet: Unable to connect to remote host: No route to host
case: soft-reboot
definition: lava
result: fail
level: 2.5.1.1
extra: ...
Connection closed
Connection closed
uboot-retry failed: 1 of 1 attempts. 'Connection closed'

Acceptance criteria

When Job completes successfully.