Force SRX to boot from usb

Hi, I have an SRX cluster running 12.1X44-D40.2. Seems like on one node the CF has died, now it boots up, enters multiuser and crashes. I did some reserch on the internet, and, according to the identical backtrace I've found, it's a CF problem (seems weird though, but the same node previously was failing to save the autorecovery, showing errors on copying the label, so it really may be the CF).

However, trying to resue the failed node, I encountered another problem: the node that is still alive (and that the cluster is istill operating on) crashes immidiately after plugging the CF card reader, and this is repeatable.

So I did another thing - I dd'ed the da0 CF from running node via ssh to a FreeBSD server and wrote it to the newly aquired CF card (this actually brought some surprise too - I got an error while reading the da0 on valid node).

So, now I have a CF card reader plugged into the SRX, but it still boots from internal media. Is there a way to boot it up from a usb ? All the document just don't focus on it, assuming the SRX should boot from usb automatically, - this definitely should work when no internal media is suitable for booting, but in my case SRX thinks that it does contain valid image since it contains valid boot loader.

Here's what I have in u-boot loader:

=> usb storage
  Device 0: Vendor: ST       Prod.: ST72682          Rev: 2.10
            Type: Removable Hard Disk
            Capacity: 2000.0 MB = 1.9 GB (4096000 x 512)
  Device 1: Vendor: Generic  Prod.: STORAGE DEVICE   Rev: 0570
            Type: Removable Hard Disk
            Capacity: 3811.9 MB = 3.7 GB (7806960 x 512)

But I just failed to find a way to tell the SRX to boot from this additional disk (device 1).