After sitting there for a long time with an USB drive the probe returned to live, it has been online for the past 7 hours and 30 minutes.
Is it possible that this was somehow related to some server side issue? I'm seeing other similar reports from at least one other probe.
This typically happens when a probe cannot reach its controller or if the controller has a problem. The probe gets told by the registration server what firmware it needs to have. If the probe is currently running a lower version, it tries to get that from a controller using SSH. Unfortunately, there are error conditions that are not properly recognized by the probe when it tries to download firmware. Typically the probe then tries to use an empty file as the new firmware. The empty file doesn't match the checksum sent by the registration server and the upgrade is aborted. There may also be issues on the probe, for example if something is wrong with the USB stick.